If you’ll make an updated translation file and wish for it to be included in the next Spark version, then attach it here. It will be enough to attach the i18n file itself. Though it is better to make a diff with only changes, so i can apply it as a patch to the source.
I have pointed where to find it in the source code of Spark as you mentioned “code”. E.g. igniterealtime/Spark · GitHub
If you want to change it for your Spark, you can also open Spark\lib\spark.jar (in the folder you have Spark installed in) with an archive program, go to i18n inside it, extract the language file you need, edit it and then add it back to spark.jar and let it repack the archive.
i18n files use unicode codes for non-latin symbols. Like: \u63a5 (some Chinese symbol). You can edit this file with a notepad, but you will have to use those codes instead of normal symbols.
I usually edit it in Eclipse which use to edit the source code. It converts non-latin symbols to unicode code automatically (i think it does, haven’t done this for a long, at least Netbeans did). But it is a huge IDE program and installing and configuring it just to edit language files looks like too much. Maybe there are some other programs (like Popeye) to do this, but i haven’t used any of them.
I’ve been using Notepad to edit the source code, also converted to Unicode format store, but after covering the original spark.jar this file, find Spark unable to open, how to do it?