The first two values after FRAME are score corresponding to Uke and Tori respectively. The third and fourth values are a little stranger, I've done some testing in the past and the most I could figure out is the following.
If Tori and Uke do not suffer dismemberments, v1=v4 and v2=v3 (value 3 and value 4 are the same as Uke and Tori's scores, but mirrored). In Toribash, a dismemberment penalises the player that suffered it by giving the other player a certain amount of points (I think usually 2000 or 5000 depending on the body part). If Tori is dismembered, v3 decreases by the amount of points that Uke gained from the dismemberment, and if Uke is dismembered, v4 decreases by the amount of points Tori gained. v3 and v4 differ from v2 and v1 in that they subtract the score that each player lost from being dismembered. The values can be negative if a player suffers a lot of dms.

FRAME x; {UkeScore} {ToriScore} {ToriScore - DMsToriSuffered} {UkeScore - DMsUkeSuffered}

Note that UkeScore and ToriScore consist of the sum of the damage dealt both by hitting and dismembering.
Cool thread. If you haven't seen Moltex's hacking tutorial it might have something useful: https://forum.toribash.com/showthread.php?t=19742 However it is quite old and the replay file structure might have changed since then.