No, it's unambiguous. "All of our users' lost funds" doesn't imply "But not all of the funds". Nor can it mean "But not all of the users".

The meaning of their statement is clear, unless they're going ridiculous and disputing definitions, such as: What are "funds", or Who is a "user"

But whether it's possible for them to honor that promise? Seems doubtful.

I find it very hard to believe that they can promptly conjure up over half a billion dollars to refund their users. Firstly because I'd ask: what were they doing with that excess capital before?

edit: Although "committed to" does not mean "anytime soon"! Perhaps they plan to issue a token of some kind, and pray they can keep going and gradually make the users whole?