Cria Cuervos/ Raise Ravens and Sant Tukaram are in already and i've added Lady Snowblood, which i'd thought was too. I'm excluding British English-language films, even if by non-Anglophone directors (though films in Welsh are of course a different matter!). I'll consider your other suggestions, when i've done more study, as most i've not seen and some titles are not very familiar, and also it's now very close to 1000 (which would be a significant threshold to cross, decimal tyranny and all that). Sorry to take this awkward stance, but if i include everything suggested the list really could get out of hand, however long you might want it to be!
O.k, i've now added A Simple Event + Lau's Pole Fighter (difficult to know which to have by the director, Tony Rayns loves Dirty Ho and i'd already been tempted by that, but i'll give precedence to you, the imdb average score precedence, and my own sense of its probably greater popularity).
I first came across Othon in John Kobal's book of Top 100 Movies- not as one of the 100, but when each critic/contributor named their least favourite film! In this case 2 chose it as their worst; Michel Ciment (who picked Sansho the Bailiff, Sunrise and La Regle du Jeu in his top 10!) and Giovanni Grazzini. I'd be interested in why they hated it so much, haven't seen it, but can imagine Straub's style may alienate quite a few critics. It's not included in my Bloomsbury Foriegn Film Guide but here's what Time Out guide has to say:
"the film can be mesmerising or irritating: irritating if one tries to force it into fulfilling preconceived notions of plot and character, mesmeric if one trusts the film-maker to lead one into fresh areas of perception". Which makes it sound both significant + intriguing.
By Straub, i'd most like to see Not Reconciled, which many hate. Chronicle of Anna Magdalena Bach was certainly worthwhile, and Gilbert Adair's book Flickers picked (the quite obscure?) The Death of Empedocles to represent the year 1987.
I disliked Zulawski's Possession, but then there are quite a few films in the canon i'm not keen on, so that certainly doesn't rule it out. I'd rather be inclusive than exclusive + overly conservative. Do say more about any you specially want to champion.