I honestly doubt it but could the "times vengeance" mean that time is literally seeking out its revenge for being manipulated. By this I mean say you come form one portal what if during times vengeance, the small amount of time allotted to us we have to go inside the other portal and search for a 6th chest. Seems like something cryptic and annoying bungie would do to us all. This could also mean that it isn't the past, present nor future, just an idea.