I dont have a clue, but I can only offer some notes... I date say that you have tested all avenues, but :-
EDO or FastPage, Parity, non parity, 60ns 70ns 80ns or whatever, Bits abd bytes and all that stuff.. there are a fair number of different type of the stuff actually, so perhaps ou need to have an exacting type?
I think that FastPage parity RAM would be the one to go for... Im sure of that, so forget about any EDO RAM.
I clearly dont know about the Atari Falcon, but I do know that the Falcon was out around the 386-486 era and that they didnt work with EDO RAM and als otaht the Apple MAcs used Parity RAM ,so thats suggesting its Parity RAM for the Atari too!
There is also knowing the memory config thats required too... Again, is it 1K refresh, or 2K or 4K ? is it 4Mx32, 4Mx36 8Mx36 or 8mx32 or 2Mx32 or even 32x32 or 36 or whatever?
You need to find out what is the best RAM to use with that board... I dont have a clue myself what the best RAM is for it im afraid.
Hey... If its any help for you, Im in the same boat with my TT RAM on my...Well, my TT I suppose? - Id like to get it up to 16MB but the 4x4MB I have does not seem to want to work with it apparently.
MSTE @ 16Mhz : 4MB+8MB : Magic & Jinnee
TT030 @ 32Mhz : 10+16MB : Magic & Jinnee
Falcon060 @ 95Mhz : 16+512MB : MiNT & Jinnee
More PCs than PC World has... Probably