The current missing troops should be the ones who was released after July 4th:
- Hellcat and Creeper
- Dwarven Slayer and Northrender
- Tal’Rae and Spider Knight
- Rock Troll
- Astral Spirit and Moa
According to @KAYA43V3R’s time scale Gems Of War Chronicle.
It seems that devs have chosen a monthly update of the chests (why?). So, maybe next week or next next week, these troops would be in the chests ;-).