First all, greetings to all the Persona fans. Just decided to share some insight into accidental fusions and more about that 'Kaiwan Skill change' madness.
I've been having too many accidental fusions to recall (around 10+) while trying to secure every possible R7 skill in-game. The most hilarious thing was that I actually got 2 back-to-back accidental fusions. These won't be secure, solid tips but I do feel like I'm doing something right, so here goes.
Been racking my brains to save 3-4 R7 skills in each persona within the compendium, and from what I gathered, these things have helped some:
1) Triangle fusion having a higher fail rate: Unless I'm very lucky, but having one back-to-back probably makes this observation hold true. Do make use of more triangle fusions
2) This will sound ridiculous, but I decided to try watching the whole fusing animation and just as the screen goes blank, I simply push the left analog button down. Was my first time literally viewing the accidental fusion completely (main purpose was getting all R7 skills afterall) and I obtained a Shiki-Ouji (2nd time from AF) [My MC is Level 63]. Guess what, I decided to do the same thing yet again, and voila, this was the back-to-back AF and I got a Decarbia (3rd miserable one from AF). It sounds ludacris but it might help
3) My other advice is to simply just keep fusing the personas you want. With this R7 collection, I always tried different triangle combos to keep the skills in different personas, so that could help you. The back-to-back one I had was using Lovers 'Udnine' + Priestess 'High-Pixie' + Death 'Mokoi' = Mithra. I did this to pass on 4 R7 skills from Udine to Mithra, as it levels up via 2 levels, it will learn the skill 'Tetra Break', so giving me a 5/7 chance in R7 skill-changing (~70%). Trust me, Kaiwan is too hard to inherit 4 skills...extremely overrated IMO.
Also, I could use some advice in awesome Level 70 personas. AF often grants you a persona close to your level. I've received a Jinn, Sui-ki, Cybele, Garuda, Decarbia x3, Shiki-Ouiji x2 and a Abaddon solely from AF. As awesome as it sounds, it's taking up an awful lot of space.
Extra helpful tips: I'm doing this on 14th July, finished the Striptease so far and pushing hard to open the Tower Arcana.
PS: For those curious, that last Decarbia of my AF forced one of the five R7 to finally change to Repel Fire, the hardest R7 for me to get. As for that VC, only got it twice.