Okay I think I've finally found a bit of a workaround for the people stuck with Kleio and Anna's threesome.
Mossrock if you're still stuck I hope this helps bro.
I did some digging in the code and it appears it might be some issue with an old event as I noticed one of Kleio's events (the one where you watch the sun rise) should increase her max love to 90%, and I've done that but her max was still stuck at 75 for some reason. Perhaps we played an old version of the game that didn't have that max boost? Eh, anyway.
1) First off you're gonna wanna make sure you can use the console (open the folder of the game > renpy > common > 00console.rpy > make sure
config.console = True
).
2) You can verify you've already done the part of the story that should have increased her limit by typing
kleio.get_flag_value("story")
into the console (Shift + O). If it outputs a 4, you've already done it, if it's 3, then you need to do the sunrise event.
3) You can check it beforehand in case this isn't the issue, but otherwise type
kleio_love_max = 180
into the console, and bingo, she can now get to 90%. Now just get her to 85% and the next time you're at the recording studio, the date event should trigger.
I noticed the dev mentioned that you need to fugg them both at least 3 times to start -- that's true, but there's a preliminary event that you've probably already done that had that requirement. The date event requires that PLUS they both need to be 85+ love. You need to do this event to get the four some events, and she'll also only keep the kid if she's at 90+ love as well.
Hope that helps, dudes.