She's been there for 24 hours??? I'd say that's INCREDIBLY normal, the stress of the flight alone!
They need to give her time. It's a big change, new people, new place, new environment/smells, and again, stress of actual moving.
I would ask them to have some empathy before they expect this dog to be "normal", it will be a process... some dogs adjust faster than others.
Ways to help? Comforting the dog, being on a routine, giving the dog a safe space like a crate where she isn't bothered, not pushing boundaries (let her get used to home/yard/small walks), I would lay off other dogs all together until she is comfortable and even then, baby steps.
The fussing and climbing is obviously just nerves and seeking comfort, I would just give her time since she is obviously at least bonding to these people.
Romeo also came to me as an adult and took a month before I think he felt at home.
IMO pushing her will makes things worse and expecting an adult dog to be totally normal after such a huge change after a few days is totally unrealistic. I would honestly question the competence of a home that would expect that.
I wouldn't expect MERLIN to be perfect/normal after a few days when he moves here, and that's with the SAME OWNER.