Welcome to the community, @Alex_Coole! :grinning_face_with_big_eyes: Sorry that this question has gone unanswered for so long.
I don’t know what (if any) limit there is to field name length, but I know how to address your issue. When building an Airtable form, Airtable defaults to putting the field name as the form text for that field.
However, you can override that with different text that’s specific to the form. Just click on the field name when building the form, and Airtable lets you replace the text with whatever you want.
This means that you don’t need to put the full question text into the field name. Make the field name something short that reminds you of the question, and override that with the full question text when making the form.