What does any of these things matter though?
It is clear (even assuming OP’s count and categorization is correct) that the commander unit sets are imbalanced and chosen not due to any specific pattern, but rather to fulfill certain commander functions.
So even if we do get a Terran commander, it is can still be inclusive of over-used units, such as Marine or Tank. I am 100% more interested in the functionality and role (perhaps even any additionally unique feature) any new commander unit sets may bring, rather than an “oh, look another marine, how boring” kind of mentality. I mean if it’s a flying Marine that can Heal, sounds overpowered but if it works uniquely to the style of the new commander then I am all fore it.