The problem with Lagrange storm clouds is that they appear to be the most rare type in the galaxy, even rarer than green gas giants. Of course, the fact that some of them have been turned into regular clouds after an update certainly didn't help.
You could try searching the IGAU public Codex database at
https://github.com/Elite-IGAU/publications/blob/master/IGAU_Codex.csv: that one has timestamps too, so you know that at least at the time of uploading, that was what was there in the system. Again, it's a problem though that storm clouds are so rare, it's not like people come across them often.
As for where you can find colourful Lagrange clouds, see this part from the guide:
"Lagrange clouds are
not independent of space-borne life; rather, they act as containers for it. If you're looking for clouds, you'll find them where the life is meant to show up. If you're looking for the
colourful clouds, you'll only find them around nebulae. This also means systems around planetary nebulae, not just inside them. Proto-Lagrange Clouds can appear anywhere where NSPs appear, they aren't restricted. Although do note that there are a few lifeforms which only appear inside rings!"
Not all nebulae have NSPs, of course. The
Catalogue of Galactic Nebulae does note which ones are known to have them, but that part might not be complete. The vast majority of real nebulae have NSPs around them, while for the proc. gen. nebulae, it's the other way around.
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