Over fifty people, an eighth—one can't consider the loss to be small, but it isn't too great either.
In Richard's view, only seven-eighths of the enemy remained, which was still sufficient to overpower Gro and his group. Once they decided to attack decisively, the result wouldn't be much different from before.
The only possible difference might be morale.
Morale is crucial for an army, especially in the age of cold weapons, where it could almost determine everything. In the recent explosion, amidst the fear and misunderstanding of the unknown, the morale of the soldiers outside the camp had evidently suffered more than the numerical loss. If the previous morale was a hundred, now it was around fifty.
After all, the destructive power of firearms was almost devastating to soldiers in the age of cold weapons.
Moreover, if Richard hadn't guessed wrong, the attacking soldiers and their leader likely knew that they were engaged in a rebellion—an illegal and highly pressured act.