Both morbid and whimsical and it works. I've run the adventure three times with Old-School Essentials. Players who are not managing risk well will lose characters as written, but there is no point where the adventure felt capricious.

I have a few criticisms. One, it doesn't make sense that Philbert is still alive if the halfling on the shelf has been starving for days -- he's got to sleep at some point. Two, capturing the golden beetle could use some detail. Three, it's very hard to put together that music matters if you don't know that there's a music box somewhere in the dungeon, even then many players will not think of it. That is fine but less is too little. Four, some of the traps or mechanisms could be improved -- the secret door to the boudoir is hard to interact with and the axe traps as well -- I replaced them with ropes tied to crossbows.

All of that is fixable. Make sure players have ways of finding out about the sea cave entrance because they're perfectly capable of getting stuck at the lighthouse cellar.