So today when I was training to do some nice replays, I discovered 2 bugs.
The first one is related to Mobs Death (haven't tested if it affects players and other entities), I was jumping back in time when a mob was disappearing after death (becoming red-ish) and it tp'd the mob to the location but then recorded it as dead from that location so it moved away (for example let's say a mob after death moves 2 diagonal blocks down) it moved 2 diagonal blocks down from that location and not the location it actually died at (let's say in the actual death it went to X: 0 Y:0 Z:0 but then it went to different coords) this bug can become annoying when making custom objects to a mob's final death location (Just right before it disappears).
The second one is about Trimming, when I trimmed a replay the loaded the keyframes I pressed play camera path and the custom item that I made became a 16x16 blank square (I used a 16x16 texture that I made that isn't blank but have some invisible space but all of it became blank not just the invisible places) after I checked the asset it was the normal one and not a blank asset, I had to change the asset to the one I'm actually using (It's the same one but I like re-loaded it) so that it could work.
The third one, I'm not sure if it's a bug or a feature but all of the F[Number] commands work.