10 days ago I was gifted this trio of Serissa foetida bonsais from a local greenhouse. They started dropping yellow leaves-I assume from the environmental change and light differences (SE window with 1500 LUX). I purchased this indoor light set-up with two 2' florescent T5 grow lights and two LED full-spectrum bulbs (staggered). It now gets between 5,000 and 20,000 LUX. My question is, should I worry about too much light? (There's really no heat because of LED). I have read that this variety does better in some partial shade to avoid leaf burn from the sun but that shouldn't be a fact with indoor bulbs, right?

Serissas are iffy.
They hate being moved around, so this is probably the cause of the yellow leaves.
Too much light is usually not a problem, unless the species has to go dormant in winter.
Congratulations, this is a nice Serissa you've got there!