I take l-theanine regularly for anxiety, and was a long time clonazepam/various other benzo user as well. I have noticed benzo potentiation from the l-theanine, though it wasn't an overwhelming change and never seemed very dangerous. I would be careful and perhaps use less temaz than you typically would.
I will add that, for me, the effects of l-theanine take longer to manifest than those of benzo's, so perhaps wait an hour or two to judge whether you need/like more temazepam.