Given the PIDIV is Method_4, there's a few possibilities, ranging from event to a static encounter. If I was doing it by hand, I would compared the PID and encounter slots, we can derive/educated guess met level and met location.
For the plugin, I am using PKHeX's suggest feature, and in the plugin I have code to loop through various games and return the first possible legal match.
So this is what it would have looked like if locked to Ruby:
In the above scenario, PKHeX reckons it was an Event Pichu Egg (hence Met level being 0).
As for what you have tried to change it to, RS Safari Zone Pikachu can only be Level 25 or level 27. It appears illegal for you as 26 is the wrong level.
This is what it would have looked like with the correct encounter details:
I probably mentioned a while back, but origin game (and other met details) were not part of the data that is stored in Battle Tower Mixed Records. The plugin also doesn't compare all the mons to try to determine the likely game.
If there's no override, it would cycle through games to try to get to the first legal match. There can be more than one legal match.