I agree. The concept of roles is no longer useful, especially after it was used to masquerade incest so frequently it has become a meme.
In this game there was no intention of even considering IC. It's pretty clear in the first interactions with Mary. It is indeed a relationship between strangers connected by a commercial act. The MC rents a property from a woman and ends up needing to live with her and other tenants of rooms she sub-Lents.
This is the usual mask for an IC patch, there's even the role customization, but, none of that really works here. As it didn't on this Dev previous game. The intention really is to NOT be a IC game. So, why the need for a Role? A Title? Why can't she just be "Mary" ____ (insert a surname), why can't the girls just be Alice and whatshername? Explain the relationship, and just address them by name, no titles no roles. Write for a VISUAL medium, not for a text based one. There's Name tags that tells us who's speaking, there's their faces and presence. You don't NEED to refer to the Role to be respectful, saying Miss "surname" or Ma'am, is WAY more than enough. As familiarity builds up, change to their First names. Done.
Just my 2 cents I guess...
Peace