A nice 'change of pace' adventure that doesn't rely on the PCs being powerful combat-monsters to succeed. To the contrary, a party of optimized combat characters who tend to ignore puzzles and traps are going to have difficulty with this module, as the challenge it presents is one they're not the best suited to tackle.

And that's fine! Different modules should be able to challenge different types of players, and an adventure that makes your best puzzle-solving player (who perhaps has a bit more knowledge of the Forgotten Realms from earlier editions than is usually strictly useful in the current edition) feel like the session MVP is good and to be encouraged in the Organized Play campaign.

One recommended tweak: instead of 'resistance 3' and 'resistance 5', which aren't strictly meaningful Fifth Edition D&D expressions of resistance, use 'gains resistance against the next source of that damage type' and 'gains resistance against that damage type for the remainder of the adventure'. This will retain the flavor of the methods of gaining these resistances, as well as be a better expression of those resistances in 5E terms.