On the question of current form - particularly for the long-distance events - I don't think the requirement should necessarily be interpreted that they have to achieve the OQS after April.
Both Dever and Keith were 23 seconds outside of the OQS so I'm a bit confused how that would indicate Keith is in form, but Dever isn't. Surely that should mean they've either both done enough to show current form or neither of them have shown current form?
When it comes to selection for distance events, I wouldn't look at them in isolation - Dever has the OQS for 5000m so, assuming he finishes inside top-2 at trials will be going to Paris. If he's already going and gets an invite for 10,000m, there would be no reason for UK Athletics to turn it down. Likewise for Warner-Judd, if she is able to get on the squad for the 5000m, she'd be allowed to run the 10 if she gets an invite.
The bigger question is whether there will actually be any invites for the 10000m - can't recall if there were any given for Budapest.