diff --git a/Meta/Lagom/Tools/CodeGenerators/LibWeb/GenerateCSSEnums.cpp b/Meta/Lagom/Tools/CodeGenerators/LibWeb/GenerateCSSEnums.cpp
index 997aa5c67b..cbcdeee7d1 100644
--- a/Meta/Lagom/Tools/CodeGenerators/LibWeb/GenerateCSSEnums.cpp
+++ b/Meta/Lagom/Tools/CodeGenerators/LibWeb/GenerateCSSEnums.cpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2022, Sam Atkins <atkinssj@serenityos.org>
+ * Copyright (c) 2022-2023, Sam Atkins <atkinssj@serenityos.org>
  *
  * SPDX-License-Identifier: BSD-2-Clause
  */
@@ -43,7 +43,7 @@ ErrorOr<void> generate_header_file(JsonObject& enums_data, Core::File& file)
     StringBuilder builder;
     SourceGenerator generator { builder };
 
-    generator.append(R"~~~(
+    TRY(generator.try_append(R"~~~(
 #pragma once
 
 #include <AK/Optional.h>
@@ -52,7 +52,7 @@ namespace Web::CSS {
 
 enum class ValueID;
 
-)~~~");
+)~~~"));
 
     TRY(enums_data.try_for_each_member([&](auto& name, auto& value) -> ErrorOr<void> {
         VERIFY(value.is_array());
@@ -65,16 +65,16 @@ enum class ValueID;
         // Find the smallest possible type to use.
         auto member_max_value = members.size() - 1;
         if (NumericLimits<u8>::max() >= member_max_value) {
-            enum_generator.set("enum_type", "u8");
+            TRY(enum_generator.set("enum_type", "u8"_short_string));
         } else if (NumericLimits<u16>::max() >= member_max_value) {
-            enum_generator.set("enum_type", "u16");
+            TRY(enum_generator.set("enum_type", "u16"_short_string));
         } else if (NumericLimits<u32>::max() >= member_max_value) {
-            enum_generator.set("enum_type", "u32");
+            TRY(enum_generator.set("enum_type", "u32"_short_string));
         } else {
-            enum_generator.set("enum_type", "u64");
+            TRY(enum_generator.set("enum_type", "u64"_short_string));
         }
 
-        enum_generator.appendln("enum class @name:titlecase@ : @enum_type@ {");
+        TRY(enum_generator.try_appendln("enum class @name:titlecase@ : @enum_type@ {"));
 
         for (auto& member : members.values()) {
             auto member_name = member.to_deprecated_string();
@@ -83,19 +83,18 @@ enum class ValueID;
                 continue;
             auto member_generator = TRY(enum_generator.fork());
             TRY(member_generator.set("member:titlecase", TRY(title_casify(member_name))));
-            member_generator.appendln("    @member:titlecase@,");
+            TRY(member_generator.try_appendln("    @member:titlecase@,"));
         }
 
-        enum_generator.appendln("};");
-        enum_generator.appendln("Optional<@name:titlecase@> value_id_to_@name:snakecase@(ValueID);");
-        enum_generator.appendln("ValueID to_value_id(@name:titlecase@);");
-        enum_generator.appendln("StringView to_string(@name:titlecase@);");
-        enum_generator.append("\n");
-
+        TRY(enum_generator.try_appendln("};"));
+        TRY(enum_generator.try_appendln("Optional<@name:titlecase@> value_id_to_@name:snakecase@(ValueID);"));
+        TRY(enum_generator.try_appendln("ValueID to_value_id(@name:titlecase@);"));
+        TRY(enum_generator.try_appendln("StringView to_string(@name:titlecase@);"));
+        TRY(enum_generator.try_append("\n"));
         return {};
     }));
 
-    generator.appendln("}");
+    TRY(generator.try_appendln("}"));
 
     TRY(file.write_until_depleted(generator.as_string_view().bytes()));
     return {};
@@ -106,12 +105,12 @@ ErrorOr<void> generate_implementation_file(JsonObject& enums_data, Core::File& f
     StringBuilder builder;
     SourceGenerator generator { builder };
 
-    generator.append(R"~~~(
+    TRY(generator.try_append(R"~~~(
 #include <LibWeb/CSS/Enums.h>
 #include <LibWeb/CSS/ValueID.h>
 
 namespace Web::CSS {
-)~~~");
+)~~~"));
 
     TRY(enums_data.try_for_each_member([&](auto& name, auto& value) -> ErrorOr<void> {
         VERIFY(value.is_array());
@@ -121,10 +120,10 @@ namespace Web::CSS {
         TRY(enum_generator.set("name:titlecase", TRY(title_casify(name))));
         TRY(enum_generator.set("name:snakecase", TRY(snake_casify(name))));
 
-        enum_generator.append(R"~~~(
+        TRY(enum_generator.try_append(R"~~~(
 Optional<@name:titlecase@> value_id_to_@name:snakecase@(ValueID value_id)
 {
-    switch (value_id) {)~~~");
+    switch (value_id) {)~~~"));
 
         for (auto& member : members.values()) {
             auto member_generator = TRY(enum_generator.fork());
@@ -137,22 +136,22 @@ Optional<@name:titlecase@> value_id_to_@name:snakecase@(ValueID value_id)
                 TRY(member_generator.set("valueid:titlecase", TRY(title_casify(member_name))));
                 TRY(member_generator.set("member:titlecase", TRY(title_casify(member_name))));
             }
-            member_generator.append(R"~~~(
+            TRY(member_generator.try_append(R"~~~(
     case ValueID::@valueid:titlecase@:
-        return @name:titlecase@::@member:titlecase@;)~~~");
+        return @name:titlecase@::@member:titlecase@;)~~~"));
         }
 
-        enum_generator.append(R"~~~(
+        TRY(enum_generator.try_append(R"~~~(
     default:
         return {};
     }
 }
-)~~~");
+)~~~"));
 
-        enum_generator.append(R"~~~(
+        TRY(enum_generator.try_append(R"~~~(
 ValueID to_value_id(@name:titlecase@ @name:snakecase@_value)
 {
-    switch (@name:snakecase@_value) {)~~~");
+    switch (@name:snakecase@_value) {)~~~"));
 
         for (auto& member : members.values()) {
             auto member_generator = TRY(enum_generator.fork());
@@ -161,46 +160,46 @@ ValueID to_value_id(@name:titlecase@ @name:snakecase@_value)
                 continue;
             TRY(member_generator.set("member:titlecase", TRY(title_casify(member_name))));
 
-            member_generator.append(R"~~~(
+            TRY(member_generator.try_append(R"~~~(
     case @name:titlecase@::@member:titlecase@:
-        return ValueID::@member:titlecase@;)~~~");
+        return ValueID::@member:titlecase@;)~~~"));
         }
 
-        enum_generator.append(R"~~~(
+        TRY(enum_generator.try_append(R"~~~(
     default:
         VERIFY_NOT_REACHED();
     }
 }
-)~~~");
+)~~~"));
 
-        enum_generator.append(R"~~~(
+        TRY(enum_generator.try_append(R"~~~(
 StringView to_string(@name:titlecase@ value)
 {
-    switch (value) {)~~~");
+    switch (value) {)~~~"));
 
         for (auto& member : members.values()) {
             auto member_generator = TRY(enum_generator.fork());
             auto member_name = member.to_deprecated_string();
             if (member_name.contains('='))
                 continue;
-            member_generator.set("member:css", member_name);
+            TRY(member_generator.set("member:css", TRY(String::from_deprecated_string(member_name))));
             TRY(member_generator.set("member:titlecase", TRY(title_casify(member_name))));
 
-            member_generator.append(R"~~~(
+            TRY(member_generator.try_append(R"~~~(
     case @name:titlecase@::@member:titlecase@:
-        return "@member:css@"sv;)~~~");
+        return "@member:css@"sv;)~~~"));
         }
 
-        enum_generator.append(R"~~~(
+        TRY(enum_generator.try_append(R"~~~(
     default:
         VERIFY_NOT_REACHED();
     }
 }
-)~~~");
+)~~~"));
         return {};
     }));
 
-    generator.appendln("}");
+    TRY(generator.try_appendln("}"));
 
     TRY(file.write_until_depleted(generator.as_string_view().bytes()));
     return {};