Hi, that's great!
Yes, I can incorporate the translation into my mod if you don't mind.
But I strongly recommend you ti learn how to use github, because it also contains pretty useful tool to highlight changes. Actually, the whole git is about managing changes, so highlighting and analyzing is essential for each git-based system.
If you want any stand alone tool, you're looking for a family of tools called "diff tools", so you can just search for suatable tools with those keywords which fit your needs. I can't advise anything particular, because I'm using git clients and their built-in tools for that.

I understand, but I have the problem that I can't handle github at all. I had looked at it once, but was completely overwhelmed, so I prefer to use RimTrans and just edit the xml.

Don't forget that the translation only affects certain lines, which are filtered out/created with RimTrans anyway. The rest of the mod, commands and all that, are 99% uninteresting, and I don't build them in, it really needs ONLY the languages-english and languages-german folders/files.

But that also means that these strings don't exist seperately in the language - english folder, which doesn't appeal to me. So I have to synchronize the original english xml I generated with RimTrans from the version I translated, then with the new english version I created using RimTrans and then with an additional tool. So I'm not using any original files from Mod.

in simple:
Create
1. download mod
2. use RimTrans for English as well as for German
3. English proficiency
4. translate german
---------------------
Updating
5. update Mod
6. use RimTrans for English
7. compare old english files with the new english ones
8. update german translation if changes available

Yes, I already found that with the "diff tools" in the meantime, I already loaded a small one. Unfortunately most of those I tested so far have the problem that they show me changes where none are (e.g. line breaks).

I've now tried Github because I understand it makes your work easier, I just hope I didn't do anything wrong there.
If you prefer, I can also send you the files (languages-german) zipped in the forum, if you like.