Simi and welcome to Sidosi! I'm glad you've found Sidosi useful for your research, and I wish I had more of the pretty much complete website revamp ready to aid you more.
If you're taking any more pointers for the history of Solresol, you can't beat David Whitwell's La Téléphonie and the Universal Musical Language
. It's the expanded "second edition" book form of Whitwell's collection of essays I have listed on the Resources page. It has countless translated excerpts from original French sources, including many scans and photos, along with Whitwell's commentary. It covers from 1817, around when Sudre became a music professor, to 1866, when Sudre's wife posthumously published his book
, at least the one we have a copy of. All the time since then, with the exception of the 1902 publishing of Gajewski's book, hasn't been documented very well, and is assumed to be mostly dead time for the language, though we have some evidence that there was a dedicated group that existed.
Anyway, to your main question for the community... I am a long-time musician, having played trumpet for 20 years, piano (off and on) for about 17 years, and picking up various other instruments that pique my interest in the meantime. I can't 100% remember the details, but I know I first encountered Solresol a while before I initially sought out more information and found the modern Solresol community (and created Sidosi as a result). I believe I was browsing Wikipedia, looking at articles related to whistled languages, when it led me to the article for Solresol. I believe that planted a seed, and some time later, I rediscovered Solresol and found the community.
As far as thoughts on the language's development, things are moving slowly, but then again, Solresol isn't your typical constructed language that is one person's ongoing creative work. Solresol already has a foundation laid, and it was successfully used in Sudre's time, but there are pieces missing that we either have to find or create a replacement for. It doesn't help that likely all of the sources from the heyday of Solresol are in French, so that information needs to be found and
translated for the vast majority of the community. Another challenge for the community is actually learning the language, so we know what does and doesn't work in practice. Again, all of the original sources are in French, and there are no good English "tutorials" for learning Solresol, though there have been efforts made.
Regarding the more technical aspects of the language's development, like I said, the foundation's there, but there are just pieces missing. One major piece is the unfinished and outdated vocabulary. Sudre left us a dictionary with ~3000 words, but there are almost 17,000 possible combinations of Solresol syllables, up to the 5-syllable words that Sudre started. There are concepts represented in his dictionary that are now considered archaic or obsolete, and of course an astounding number of concepts have been invented in the past 150 years. As is the case for many conlangs, multiple members of the community want to translate works to Solresol, but have trouble finding the correct translation. Two aspects of Solresol that make it unique, but also make vocabulary work a challenge, are that its vocabulary is meant to be unambiguous and that reversing a word's syllable order creates its opposite (simi = hello, misi = goodbye).
Anyway, you can find other members' experiences and history in this Introductions section of the forum, and I invite you to join a Discord server a member set up, which has a more active chat room dynamic: https://discord.gg/2jaRATy
I hope this book of a post helps you!