I accepted the quest after killing those muck monsters at the Toadem and somehow Smitty still needs me to go there and look around. So I went back to the toad village where I talked to everybody about everything and even touched the Toadem again. Nothing. I still need to 'look around'.

Is my questline permanently broken or is there a way to finish the quest? I don't care if I have to cheat or edit a file, I just want to progress to the next guild quest.

I think the quest just need you to talk to the shaman shinwiki in the hut where you can enter the tunnel to the toadem. If you talked to him about everything this should trigger the completing condition. Are you sure you talked to shinwiki about any topic, especially "ukabu"?

Very odd. The first suggestion I have is to get the quest on another character, if you are able, then go and Ukabu everyone again (especially Ekbu). If that doesn't work, you may need to Reset Adventures, clearing all of your quest progress, but ultimately netting a good bit of extra experience. Try to clear any enemies nearby before either above approach, should you decide to attempt them. Hope you can solve it!

I'm sure I talked about every topic with Shinwiki and Ekbu. I'm not sure if this is just my game being buggy, but I can't really talk to Ekbu. He just tells me he doesn't want to talk to me and wants me to leave, even after repeating "ukabu". He never attacks though. Do you know if it's possible to restart the questline by creating a new character and joining the guild with him? I'm really not sure if I want to reset the game and go through two whole dungeons again.

I finished this quest with the Rogue (after he got the Ninja class) and I did like this:

With the Rogue selected i talked to the guard about Ukabu
Always with the Rogue selected i went to the shaman and talked about Ukabu and Evil
Went to the Toadem and always with the Rogue selected i touched the Toadem pole.

Worked like a charm!

Thank you all for your help! I'm really glad I don't have to do the Serpent Temple again. And those horrible mantraps...

On the topic of mantraps: use burning haze spell. Never allow them to get close enough to use their attack. As soon as you see their shape appear on the horizon, cast burning haze on it. It will stop the mantrap from moving while the fire is ticking on it. Two hazes should kill a mantrap.

That's exactly how I dealt with them. Only issue was the 'Never allow them to get close' part, because two were out of sight behind some trees. I'm not sure what the developers were thinking when they created those things. Seems like the only reliable way to kill them is cheesing by casting spells and immediately running away.

Invisibility spell and close range shoul do the trick too, they seems not fire that nasty spell if you are in melee combat