Does this sentence "much as I had enjoyed my adventure, it was good to be back." have different meanings?

There is only one meaning the sentence can have. It's a statement in the past tense about the way that the speaker felt when he returned home. If he were speaking to someone at the time of his return, he might have said (in the present tense): "Much as I [have] enjoyed my adventure, it is good to be back." When he is (later) talking about his feelings about returning home, he has to change the tense of the two verbs to express what he felt at some time in the past: "I [have] enjoyed ... " becomes "I had enjoyed" "It is good ..." becomes "it was good" (although "I have enjoyed" or "I enjoyed" is, itself, in the past perfect form, the auxiliary "have" is in the present tense and, in order to match "it was good", it must be changed to a sort of 'double past' tense by using "had".) If the speaker meant to convey that he had come to the end of his adventure, but had not yet returned home, he would say: "Much as I have enjoyed my adventure, it will be good to be back." If there were some doubt about his returning (soon or ever), he might say: "Much as I have enjoyed my adventure, it would be good to be back." If the adventure were not yet finished but he was looking forward to returning home, he might say: "Much as I am enjoying my adventure, it will be good to be back." The sentence is a good example of a way in which one uses the comma to take the place of a conjunction. The simplest form of the statement would be: "I had enjoyed my adventure very much BUT it was good to be back." It's also worth pointing out that "Much as ..." in this construction is quite different from the comparative phrase: "As much as" (which means 'equal to').