hey thanks for the question. Neither modding or raising the level cap are in the plan for the game at this time. I'm working on another game now so likely only fixing bugs on DOE for the foreseeable future.
Without knowing anything about your game, I would assume at 17% complete that there is still quite a bit of content. The game does allow you to grind up characters without completing the story objectives. Mission difficulty will scale down with your team so if you take a few rookies along or basically switch to all rookies then you won't get penalized for the grind. There are 9 total character classes (guessing you only used 4?) and 5 different enemy classes (have you fought Cultists or Mechs?) and lots of other stuff to unlock so I'm sure there is more to see if you want to keep playing