@ 3246251196
If someone else has tested the 2412 as 15KHz friendly, then all you should need is the adapter. BUT - see below.
To expand upon David Wright's comment, I have tested the 2320 in 15KHz and it works. Interlace "works" on that display, but the picture quality is very poor. The 2412 may behave similarly.
One important thing to bear in mind: my A2000 would not boot with a generic 23-15pin adapter plugged in. Something to do with a missing genlock signal if I remember the discussion here about it. The official Commodore "silverbox" adapters contain additional logic that circumvents that issue and work fine. Those generic adapters work fine on AGA Amigas however. I don't know if other ECS Amigas behave like the A2000 with the straight-through generic adapters.
The Amibay thread you linked refers to a version of the adapter with buffered sync that seems to serve as a drop-in replacement for the Commodore adapter. You may want to get one of those.