I have had several R695s
I never had a problem with the doors and like the fact that they close firmly
Given your daughter's age, imo it is good that she can not open the doors herself because rats are delicate animals and also little escape artists … children need to be supervised when handling small animals such as ratties
If the latches are that difficult, perhaps they need to be bent a bit?
I have never heard of anyone unhappy about the doors before and never heard of anyone creating hacks for them.
There is info on here regarding martins cages, and posts with people's pictures showing how they set the up.
I found that covering the full level with a thick piece of linoleum and covering the balconies with dollar store dish drain trays cut to fit and attached with cable ties worked well for me (since wire floors need to be covered so that they are solid) The only issue I had with the cage is the c-rings, on advice from other martinscage owners I assembled my martins cages with a few hundred zip ties since the c-rings will rust