My apologies, I didn't notice you were on an older v14.1. Yes the older Editors version did only allow input based on a regular expression syntax. Since it was made with a custom textbox implementation, it allowed us to do some input blocking like that. The downsides of this original implementation was that it used a lot of elements and bindings (making the edit boxes somewhat resource intensive), it prevented any kind of alternate input and could have issues in some cases where certain cultures had extensive changes from the norm, and didn't support things like IME input.
When Editors were refactored in v17.1, we greatly simplified the edit box design so they are much more lightweight. When many instances are used in data grids, they now load a lot faster and with less memory. They are more freeform, allowing for more expressive text input, and support IME input. They still support spinning values, and navigation between parts. And the design is compatible with UWP. The only main downside of the new design is that we lost the ability to restrict input as it's being typed, which is what I was originally referring to.
Looking at the TimeSpanHoursPart code in v14.1, it seems like the code that validates an hour can be parsed just checks for 0..23 range and isn't considering the format to possibly restrict to 0..11. I don't think there's a way to alter that logic externally, at least easily.