So thats something you need to be working on then. Once evolved the girls will pay you back in dividens believe me. The escalation is not steep but events are exception ot this rule. And its strongly advised to try and get at least few of your girls evolved so you have one "run through" team that can survive the map to get you the victory rewards (even if the others die in the process (as long as you get what you need you can always try to 3 medal the stage at a later point).

There are 3 types of events mobs
-DPS ones - most of the times you encounter these. Low lvl mobs that deal SHIT tons of damage, regardless of their low lvl.
-Tanky ones - they do not deal much damage, but can soak quite a lot of punishment from your team.
-balanced ones - as the name suggests they are balanced, have decent defense and deal moderate damage, you wont encounter these too often in all honesty.