I DO see it as an issue. It is all well and good to say that level 3 is only a rec level and it doesn't matter; but it sounds like the girls are starting to train level 4, which is a required level and going ahead and working those skills is important for a kid who is coming up on her last meet of level 3. It doesn't sound like it is "just" that these two kids have been given the chance to train some with the 3s. They competed a season of level 2 and were moved up to level 3. Now they ARE level 3s, almost done with their season at that level. Somehow some days of the week there is room for them with the level 3/4 group; but not other days? On those days are there less coaches or something?
If the girls have competed a season of level 2 and then were moved to level 3 then the gym should figure out a way to have room for them with the level 3s. Even if they can't do that, then they should have them working level 3 even when with the level 2s. They are NOT level 2s getting to work up, they ARE level 3s. They are almost done with their level 3 season. What happens next? They are level 4s only allowed to work level 3 skills 2 practices per week?
For my younger DD she is training level 4. She has 3 days of practice right now. Two days it is just the girls training level 4. One day all of the compulsories work together. On those days the different levels still train their level. So my DD might run through and do a cartwheel and the level 2s might end up sticking with that for a bit; but the other girls do one and then move to round offs. Once they have shown they have that, they move to ROBHS. If they are working say, beam routines, my DD would work the level 4 routine, NOT the level 2 or 3 routine. It makes no sense for these two little girls to be sitting on the side with the level 2s, watching the level 3s do their routines instead of having them do a routine run through too.
The whole set up would make me not happy. And that the coach wouldn't talk to me about it would make me even more unhappy. If the coach in deed wasn't willing to talk about it and come up with a better solution then I would start to consider that the gym isn't the best fit for my child. Most gyms around here try to really push the young kids who show early talent, not hold them back.
Oh, and while level 2 and 3 are both rec levels, they are very different levels.