Well this is bit sad. Basically ordered wrong switches.
PCB mount isnt required but will help with alignment.
Here's what I've done in the past with plate mounted switches:
1. Install switches on 4 corners to provide some structure, don't solder yet
2. Install 1 row of switches and keycaps while checking alignment, switch seating, and excessive gaps. Make the appropriate adjustments
3. Solder one leg per switch and check alignment again. Make the appropriate adjustments
4. Solder other leg of each switch
5. Repeat steps 2-5 till complete
Sent from my SM-G955U1 using Tapatalk