Bandits that decided to attack a village that had set up fences and defenders anyway. You can't just assume they'll completely rout because they're bandits. Especially in this case they're backed up by armored well trained soldiers.A sizeable portion of the opposing force consists of bandits, who will probably get routed when facing an unit of trained and coordinated fighters.
Even if the bandits routed, that's still at least twice as many, maybe more against Valerie's group.
Valerie's group would have to not only catch but go ahead of the rebel group to set up a defensive position. If the rebels are running to Wallendorf to avoid Alexandra's army, they wouldn't bother with 30+ people desperately chasing after them that was hours behind them.The ousted noblewoman's clique is also somewhat preoccupied with trying to hurry over the border with loot, slaves and possibly some wounded slowing them down, meaning that they're probably not interested in responding to smaller threats with full force.
So yeah, if they're on the defending end, or have favorable terrain limiting the size of attacking force, then they might just do it.
And even then, the characters think it's suicidal to chase with only 36 troops. Valerie don't count because if she died then the mission is fucked, so she'd have to be kept out of the way and protected.
You and @GryphusOne can say, "Oh they might win 3:1 odds if etc" but the characters already believe it's a fools errand.
And again, author is probably going to have the rebels show up somehow nearby instead, because Valerie and MC aren't going to win a pursuit against a much larger army.