Children's chapter/MG/YA Fantasy, early 90's/80's. Up in a yellow(?) tower/castle main character must choose between 7 (?) doors

[Gulari]

Don't remember if main character is a girl or boy, or maybe many? Maybe a girl and a boy? But he/she/they are on some sort of quest. Towards the end they are up in this tower/castle and must choose the right door of 7(?) doors to continue. On the cover of the book there is a yellow castle/tower with the sea in the background.

It's not "seaward" by susan cooper. I thought so few months ago and read it, but no.

[Lobstergirl, au gratin]

Gulari, are you still looking for this or did you find it?

[Lobstergirl, au gratin]

Lobstergirl wrote: "Gulari, are you still looking for this or did you find it?"

No response in 2 years. Moving to Abandoned.