Is sentimentality a moral flaw or not?

It is one thing to identify the meaning of the locution ‘is sentimental’ (i.e. to provide a definition of the term), but quite another to establish whether in some particular case someone or something is or is not sentimental.
We all seem to agree that ‘is sentimental’ involves disapproval of some kind.
The disapproval has something to do either with the cognitive powers of the allegedly sentimental person: the emotions are shallow, or he has a simplistic worldview which makes him more prone to respond to events with emotions reserved for events of the same kind but of a more extreme nature. The correction needed would then be of an epistemological nature.
Or the disapproval pertains to how the sentimental person in his response relates to other people. In this case, the correction would be of a moral nature.
The first case does not seem particularly interesting, philosophically speaking. Not more interesting than a case of a colour-blind person reporting about the colours of the world.

The more interesting debate is about the second case.
One might want to debate whether the sentimental person can be accused of deliberate insincerity, but that question might be answered through a Wollheimian approach in terms of the lives one leads as a person. Whether we want to present an image of ourselves that involves easy success on account of emotions that were not lived through but claimed nevertheless, i.e. of a sentimental conduct.

One might want to argue that ‘is sentimental’ involves an aesthetic judgement of some kind, with no moral relevance. That might be a third way to define the disapproval involved.

Then again, being morally assessable (in negative manner) in a certain act does not turn one into a morally bad person. We sometimes cry after certain sentimental films, and know that the story or the aesthetic quality of the film isn’t worth it. Yet, we cry, and we realize our emotional response is shallow. The shallowness of that response is morally assessable, but we do not worry about it; we do not think that, next time, we should be more restrained.

Is our disapproval of sentimentality universalizable?

Why wouldn’t our disapproval of sentimentality be universalizable, i.e. hold in all relevantly similar cases?