So after today I got annoyed for the first time by that "there was an error while reading your subscription information" every 1-2 hours and a complete freeze of the game with it, I started looking for newer versions, with the last comment on tamrielfoundry guiding me here. Now the problem is, that ESO doesnt even launch on 1.5.3.3. When I try to use x86 version there comes an empty window with the title bar saying "hook64 Exception", in x64 I can only see eso64.exe popping up for a second in my task manager.
So I checked back the old version I downloaded on December 14th from tamrielfoundry, to make sure I havent messed up anything and voila: this one still works! Of course with giving me that subscription error.
I wanted to try different versions between, but honestly, what are the patchnotes for, when theyre all linked to the latest version?

Good luck with fixing and sincere thanks for all the effort youve put into this project so far!