I'm not sure how specifically that would be an issue for the cybersyn concept, as that would, I assume, mostly be a way for communities to show what they have in surplus for others in need, and what they require for themselves. In a gift economy, there's not much incentive to game that, AFAIK.

As those problems apply to the food-bank option: As much as I personally dislike crypto currencies/blockchain ledgers, it is an example of a (poorly) decentralized market-like system, though it happens to almost always be used for scams in our current society, due to profit motive.

If the food-bank fake money option was to be employed, it seems like it'd be possible to develop a method that is able to keep track of who bid on what, and who has what available each day through a decentralized fake-money system without the obvious downsides of crypto currencies (As an example, there would be no reward for keeping track of the ledger, so no one would have any incentive to create giant computer farms). And like the food bank system, at the the end of each day, it could redistribute all spent funds across the participating federated communities:

For Feeding America, an important wrinkle was a clause that redistributed to all members the sales proceeds at the end of each day. At midnight, any fake money spent on a given day was split up and returned to food banks. That went a long way toward assuaging disappointment a food bank might have felt after losing out to a higher bidder, as everyone benefited from the higher price paid.

However, it's possible that a market-style system may not be ideal, even under a gift-economy, it's just one potential idea.

As for:

Not to mention how to solve the multiple identity problem of federated systems.

I'm not sure how the multiple identity problem would be an issue in a federated system, could you elaborate on that more?