I was proud of myself for collecting 5 ingredients and felt confident going into this challenge. I quickly ruined all of them. I didn't have any bonuses. I tried rolling over and over until I could do it successfully. It took 31 tries. Did anyone else have this much trouble? Did I roll exceptionally poorly or are the odds just that bad? Thatch has a -2 to Con and Wis, so that's a disadvantage  

the basic math shakes out to be pretty much weighted against you.
The chances for success (without succeeding in the instruction task and ability modifiers already applied) are:
60% to succeed in grinding the herbs
45% to succeed in infusing the oil
40% to succeed in mixing and emulsifying.
So your chance to succeed in at a single salve at base level is

60%*45%*40% = 10.8%

with the successful instruction task it boosts each chance by 10% so it shakes out to

70%*55%*50% = 19.25%

It is definitely a tough challenge and the odds for a single attempt were against you

Thanks for doing the math. I suspected it was something like that.

i did ok ingredients and got 3. and successfully did my 1st run but the other 2 got ruined. the note bonuses helped but my rolls sucked big time  

I got behind so I just did this page and it was incredibly frustrating. I started with 4 ingredients, +0 bonus to rolls and 1 of them got to the second (Infuse) stage. I get challenge but this was stupid-hard. Any DM doing this would earn the scorn of their players, and the creator has earned mine. I already kind of hated Thatch and ending the week like this in no way redeemed him. Definitely not choosing him to continue the campaign.