Is there a way to use a number of frames it took to beat the game and convert it exactly into RTA timing? I made an AISSON Tas and I'm curious how it compares to the record.

Remember the frame that 400 appears (197 in FCEUX, usually) is the starting frame for RTA timing. The last frame in RTA timing is when you touch the axe and everything goes invisible.

Then divide the number of frames by the number of frames per second, 60.0988139 (found in the description of my any% run in case you ever need to find it because that's where I always go to get it)

Yes it's: Total frames / 60.0988139 = Time in seconds