Yes it will affect the sizing in some other places of the operating system. But it shouldn’t change the sizing of everything. It is not simply turning off all scaling.
The fact that some other things in the operating system display can be affected is mentioned in the tweak documentation, which is unfortunately spread out over the YouTube video, video descrption, Facebook post, Facebook comments, and more than one thread on this forum.
Some people feel that the benefits are worth it. Those that don’t can easily undo the two registry changes. It’s up to them.
I personally much prefer the crisper display even if some things are a bit smaller. But other people may have a different situation.
This isn’t presented as a perfect fix, but rather a workaround.
It is my hope that the Paratext developers will be able to come up with a patch that fixes the issue for everyone.
I hope that helps.