No it is not correct, for two reasons. First of all, the 36 amps that leaves the source on Phase A will return to the source on Phases B and C. Simply put, it's the same amps. You can't see 12 amps on each of the three phases and add them up to get a "total" of 36 amps. In this context, the word "total" has no meaning.
More importantly, however, it was not correct for the person creating the panel schedule to assign load in units of amps. It is not impossible for that method to end up with the correct result. But it is also not impossible (and is even more likely) that that method will end up with an incorrect result. If all loads are single phase or balanced three phase, I believe the final totals would be correct. But if you interject a few single phase 277 volt loads or some imbalanced three phase loads, all bets are off. The basic reason for this is (brace yourself!) "Amps plus Amps will not (necessarily) equal Amps." The three phases do not each reach their peak values at the same moment. For a balanced 3-phase system, when Phase A is at a positive peak, Phases B and C are both negative, both equal to each other, and half way back from (or heading towards) their negative peaks. Look on-line for a graph of three phase current, and you will be able to see what I am trying to describe.
On the other hand, KVA plus KVA does equal KVA. You can be confident in getting correct results.