If what I read are "light" novels, they sure don't look like it, just too long to finish at all sometimes, aaand bcs they're mostly Chinese, they have very slow starts, those are the hardest to overcome, wuu >_<
I'm not sure, if I read any true light novel, that was addapted to anime or manga. Maybe Yokozawa Takafumi no Baai was one, but that was very long ago.
Quite recently I finished all chapters of manga The Beginning After the End and bcs I just had to know, what was next, I actually found its novel, which was one hell of a long one surprisingly (and ongoing) >_< sooo, bcs I was too lazy to read it all over again, I started reading it right where I finished the ongoing manga, muhaha. It wasn't a problem after all, things were very accurately addapted, so I even knew what was happening XD
What I would like to read in the future would be a light novel of Dr. Stone and that is Dr. Stone: Hoshi no Yume, Chi no Uta. But I just couldn't find it anywhere yet, so have to try harder I guess... :
Might post sth more usefull when I actually read some proper light novel :