You speak right out of my heart! Fernando tried to speak with LS team but AFAIK with no result. Take a look at https://www.linuxsampler.org/faq.html
Commercial use is prohibited - no question. I think this is a really good idea because LS engine is powerful - but FluidSynth and other software also - and they have proven licenses.
So we told them what Zynthian is and asked if we had right understood that Zynthian does not need a license. The result was something like that:
If Zynthian sells kits, LS sees the project as commercial. And Zynthian has self-commited to be commercial, because we had asked (like: if you ask, you have something bad in mind).
This is my personal point of view - Fernando may see this different. My favorite after some emails was: We may get a license for less or no money - but we were asking to use it for non-commercial.
Altogether: It was a complete disaster and the current problems, we now have, may not exist if we haven't ask.
So, again: I would really have fun to use LS and create plugins - but they should have a license which is reliable and not depending on how to ask for using their software - and perhaps of the rating of the person who reads the email.