You have quite the busy list there! I am extremely envious! I was actually about to ask why you did not have German listed, until I saw that it was your native language. I really am at a loss of words: this is an outstanding feat!
Well... you know... I do share your passion for languages. Just wanted to mention a little thing at this point: Somebody gotta stay humble, so... you know... praise, and especially a not-so-small one like this one... wouldn't... be necessary. This man simply is grateful for what he could say that it has been given to him. What I just said, I do mean it. But no offense intended of course, not the slightest one.
You would learn a language based on someone else's suggestion on top of the 13 languages you're already studying? Where do you find the time for all of this!?
Well... the way this person (even if it has been a looong time since I was a child, I sometimes simply feeling like speaking of myself in the third person. ) does it, it is taking far, far less time than it seems. Not at all studying all of them at the same time. Not at all aiming for Fully Advanced Mastery of any of them.
Also, the main focus is on reading and writing for now. I currently only can use some of them in a (spoken) conversation. And even for those, the speaking ability is severely lagging behind the writing ability, and that one is lagging behind the reading skill. So... it really isn't as much as it may seem. And in order not to create a somewhat false impression maybe, I stated that it is mainly about reading and writing in my list. Also, if you would like to know some more details, they have been mentioned in a previous reply in this thread. This would be the direct link (although it is a bit long-ish) : https://forum.language-learners.org/viewtopic.php?p=120611#p120287