The Bug:

The "," symbol that exists after every color within firework star item tooltips is untranslatable and is missing a translation key.

Every language has its own rules that it follows. This ranges from spelling words differently, to using different punctuation under certain circumstances. Throughout the game, different languages can have symbols translated differently, therefore leading me to believe that this is a valid internationalization problem. For example, take the "options.controls" translatable text component which reads "Controls..." in English (US), and "按鍵設定⋯⋯" in Chinese Traditional, Hong Kong. As you can see the periods/full stops used within the Chinese Traditional, Hong Kong translation are completely different from the ones used in the English (US) translation. With this piece of knowledge in mind, some languages may interpret the use of the "," symbol differently.

Steps to Reproduce:

1. Attempt to search for the existence of this string by using this search filter on the official Minecraft crowdin project.
2. Take note as to whether or not the comma used to list colors within firework star item tooltips is untranslatable.

Observed Behavior:

The comma used to list colors within firework star item tooltips is untranslatable.

Expected Behavior:

The comma used to list colors within firework star item tooltips would be translatable.

Code Analysis:

Code analysis by Avoma can be found below.

The following is based on a decompiled version of Minecraft 1.18.1 using MCP-Reborn.

public class FireworkStarItem extends Item {
   ...
   private static Component appendColors(MutableComponent $mc, int[] $i) {
      for(int i = 0; i < $i.length; ++i) {
         if (i > 0) {
            $mc.append(", ");
         }
         ...

If we look at the above class, we can see that the comma used to list colors within firework star item tooltips is hardcoded, and as a result, is untranslatable. This is evident through the following piece of code:

append(", ")