Join-in-progress in this mode is rather tricky.
I joined the match, when the enemy already started planting the 2nd bomb. I was on 30 or 40 seconds join-in cool-down.
When I entered the match, I only had 20-40 seconds left, but I spawned the a spawn point, so the enemy already planted their 3rd bomb.
Results were really bad. I Recon managed to plant all 3 bombs.
I recommend the following changes or possibilities:
you can skip the cool-down timer, if a player just joined the match in progress, if you press some button, so that you can immediately deploy on a battlefield.
reduce time, where you can still join Detonation mode in progress by 1 minute
don’t allow join-in-progress, if at least 1 station was already destroyed