Actually if you feel you must use the perfect tense, you would use the past perfect in the second sentence, because it describes previous action that takes place before some other (unspoken) action:
She had left too late to catch the bus.
The problem with your example is more the first sentence, where the present perfect is not really justified in this context. Normally a native speaker would say simply:
I wonder if Mary is/got/arrived home yet?
The present perfect ("has left") is fine, but not if you assume it's been long enough for her to get home. The present perfect suggests very little time has passed since she left:
I wonder if Mary will get home OK? She has left too late to catch the bus.
Note all these are more about contextual agreement than grammar. The perfect tense always implies a temporal relationship, which should make sense.