There is no such mess in path, path requires you read secondary tags to get to the type of way. Your proposed categorization is not going to work out, as ways will fall into several of your descriptions at the same time.
A mtb trail is not much different to a hiking trail. The only difference might be in the legal usage. So how to tag such way, which is legally allowed to be by mtb and for pedestrians? From you posts I assume it’s not shared_use as you intend this to be like “flat, maintained” footway/cycleway.
How would you tag a way like below in your system?
