So, is it really true, that whenever a Hero would recover one or more strain without having currently taken any strain, instead that Hero recovers that many wounds? For whatever reason? No exceptions?

If an ability uses the recover term, yes, when an ability recovers strain it recovers damage for each strain not recovered. This applies to heroes only.

Non-heroes cannot recover strain. If they recover strain, it does nothing.

There is at least one ability that removes strain tokens. That is not recover, and thus works only for strain tokens. (Murne's Figurehead allows to target only heroes with strain tokens, so it cannot recover damage either.)

Thanks a1bert - Murne was the exact reason I was asking. So Figurehead can't "heal", but Rebel Propaganda" can? I feel kind of sad about this - I thought MHD-19 was THE healer of the bunch, but it turns out Murne can be almost just as good a healer. I thought she was a diplomat!

Ah, that was the other ability... Read Rebel Propaganda - it allows to discard strain tokens, not recover strain. So, it doesn't allow to recover damage.

Gideon's Rallying Shout uses recover.

Great, thanks.