Random is as random goes.
First revival event for me when I get both girls with free combat points, with a day to spare. Unbelievable luck, with two girls out of 2 spins of Event Pachinko as well - no Tachibana for me, no kobans left for another go at Pachinko.
The revival daily missions rewards, though, is a big letdown. With the new power of rainbow legendaries, epics are essentially useless now. These rewards could just be cash as of now - so the special design and look of the items is kinda wasted on items that nobody will equip now. I feel they could introduce some randomness as well in the rewards, maybe by including at least one legendary with a random roll, and the other items randomly rolling as well - boosters/gifts. At least something that could be used, rather than just cash equivalents.