Once tried to book a NW flight (now part of DL) from BDL to Hawaii on HA points. They were very nice on the phone but said I would need double points to redeem that award; which I did not have. So I normally use my HA points for a HA flight from a western mainland US city to Hawaii and back. Normally would use end to end ticketing with an overnight in a gateway city going out and a really long layover on the return (change clothing and get breakfast at an airline club). Ticket to/from western city would be a discount ticket if I could get it (usually Las Vegas was really cheap).

Some suggestions for what it's worth (probably not a lot ).

1. Sounds like you're flexible on European destination. Maybe see if they will honor a miles redemption to another destination that's easier to get?

2. Try a different carrier? HA has an agreement with Virgin Atlantic from the mainland to the UK. Virgin Atlantic may not be as strict on award tickets as DL. Maybe use HA points for a combination of HA to the Mainland and Virgin Atlantic to the UK (and possibly onwards on a no-frills carrier like RyanAir). Ideally have them do this on the same itinerary to avoid potential end-to-end ticketing issues.

3. Do end-to-end ticketing with stayover or substantial layover in case of gremlins? Fly HA to the mainland on points and then transfer to a paid discount ticket to your destination if cheaper?