I don't have the CGs I need for Lace's events, that's why they won't be advanced in the next few updates. But the events are already planned and will get into the game eventually. :)
There will be no new main party members before the time skip. Most likely, some side characters will get into the party after the time skip, but until we get to that point the group will stay with the current 12 members.
I already have years of work on my to-do list. That's why I try to avoid adding more complex systems or mini-games, and instead focus on the things I've already started or planned.
I'm probably going to re-do or improve the arena, but it's not a priority and therefore won't be done anytime soon.
The game has been in development for many years and with a way smaller budget at the start. That's why some of the older CGs aren't on the same level as what I'm getting from my artist nowadays. Several of those are planned to get a re-work at some point.