I’m currently spending my quarantine working on the language for my novel. The language is alien-like, so I wanted to make it extremely difficult in it’s phonology. There are several trills. The trilled L, the trilled Th, and the trilled Q. I started making an IPA chart to show my aunt, a linguist, in order to get her feedback and criticism. But, after searching through many many articles and IPA sounds, I couldn’t find anything similar to the trilled l and the trilled th. I called my aunt, seeing if maybe she had heard them before. She was shocked to hear me pronounce them and she couldn’t do it herself. Does anyone know of any languages that have these sounds? The trilled l is just an l, but trilled, there’s nothing fancy or foreign going on. Same thing for the th, it’s just a th (like “that” in English or “ddraig” in Welsh) but trilled. Q may be a little harder, as it’s a guttural sound but still trilled (somewhat like the breathy r in some French accents but still not similar enough to be written the same). Is anyone else able to replicate these sounds or at least can refer me to languages that use these sounds?
Regardless of the fact that you've described physical impossibilities, if you can do them, that suggests you mis-analyzed the sounds. There are very many strange sounds in human languages. The first step to doing something with these sounds is to actually capture them, meaning, make some decent recordings (preferable in the context [a__a]). Those sample can be analyzed subjectively by qualified others who have experience in auditory analysis (perhaps your aunt), and acoustically by anyone who knows how to do acoustic analysis (e.g. using Praat). It may not be possible to recover the physiological events from the recordings (it may require somewhat invasive techniques), but acoustic and auditory analysis is the starting point.
I am tempted to call the L example a "buccal trill". This may be what Lovecraft was uttering when he pronounced the name Cthulhu (there don't seem to be any authoritative recordings). The test is, when you produce it, do your cheeks rapidly bounce in and out (presumably on one side)? I agree that it is a trill, which implies a narrow constriction and an alternating cycle of pressure buildup and release as the active articulator is blown aside (reducing pressure, causing the articulator to make contact again, leading to pressure buildup, and so on).