Don't you think these two missions have a mistake, because if sauron keep 2 (minnions or monster) on perilous locations (any shadow stronghold), it's impossible for the heroes to achieve their missions.

Sauron must still attack a hero during the Ambush Step, so hero ends his turn in the location, Sauron has to either move the minion/monster out of the location or fight.

Can't the heroes just choose to fight in their travel phase? We played it that way since more than a year now^^

A hero enters a perilious location where also a minion stands, Sauron has to choose if they fight or the peril is resolved. If he choses the latter, the hero may still choose to fight afterwards. That makes the most sense to me

Doom1502 said:

No, it's Peril or Combat, then, if your turn didn't end, exploring. Only time the heroes really have a choice in if they want to fight or not is if a minion/monster is in a non-perilous location, heroes know that by going there they are forcing a combat.

Ok, I worded it bad. What I meant was bound to the following sentence in the rulebook (p10)

Note that a hero may perform this step (repeating the
sequence below) as many times as his hand of Hero
cards allows.

Which means when the hero chooses to move to a perilious location that also contains a minion/monster AND sauron chooses the peril, the hero may then again trigger the combat/peril step and now the fight begins because perils are only resolved when moving in.

But I think you're right, I misinterpreted that part. (But I think we will keep it as a houserule, not beeing able to start a fight with a minion standing next to you just seems like a glitch in the game)

No, the heros would have to move out and then back in to trigger a combat.  Then Sauron gets to choose if it is the peril or the combat that will take place.