For some Yes.
I'm not referring to whether they have statistics about their reserve or not, but whether we can verify that the number is correct. At best, we can read some documents here and there and do some guesswork to see if the flow of money is consistent or not, but I'm pretty sure it is impossible to count the money since we don't have any access to that. Unless the exchange posts everything publicly and maybe does something like a livestream, we can't really be sure of anything at all. I think this can be said for any centralized service really. If that's enough for you, I'd suggest you reconsider it. Track records of the market show that exchanges are full of fuck-ups here and there. CMIIW.