For this manga in particular, please observe how much care was taken to establish Rinne as a motherly and caring individual, and compare it to how many dommes like being called “mommy”.
In this context, she's being called "mommy" because she has an honest-to-God motherly feel and attitude. In contrast, dommes may be called "mommy" as a way to praise her context-specific dominance. This is also a kind of story (at least, at this point) where it's the normally subordinate that pursues the normally superior-- if she's not herself outright being the one "taken care of", then they're developing a relationship of roughly equals where he ironically has the edge due to his assertiveness paired with her passivity (for lack of a better word).
That moniker may be foreshadowing for something along the lines you're thinking-- I can't rule that out, but it'd be a pretty significant twist (it'd also be odd, because the point of the irony of making the subordinate the pursuer is to legitimize the relationship as much as possible by making it clear that the subordinate wasn't manipulated into the relationship through their naïveté or coercion).
Also: C'mon, mate, you don't get to mention those tastes of yours and not mention 3-4 of your favourite titles.
- Neko no Otera no Chion-san is probably my favorite one that leverages this premise. Everything's straightforward yet appropriately gradual, nothing's overplayed, and the protagonist actually has to prove himself as someone of comparable maturity to the heroine.
- Yofukashi no Uta is really engaging as a whole, and in its age gap relationship... though the actual age gap effect is attenuated by the fact that the older party isn't human and oftentimes acts as if she were an agemate.
- Kimi no Okasan o Boku ni Kudasai is one title I appreciate because it's both fairly grounded (the heroine is a widowed mother) and uses the romance angle (which is still progressively and ultimately realized) as a means to catalyze the protagonist's induction into proper manhood.
- Bite into You is engaging, though perhaps a bit more erotic than I'd like-- there's a certain "gap moe" (as they say) in the heroine being able to be mature while being able to act endearingly childish.
I mentioned younger men pursuing older women as something I like, but it isn't bad when the sexes are flipped, either--
Shiota-sensei to Amai-chan has a younger woman pursuing her older male teacher. Technically, they're dating with the proviso that they break up at at the slightest outside suspicion of their dating, but their relationship is very chaste even in their privacy-- the heroine's antics are just cute rather than provocative. It's extremely charming.