Eudimorphodon was capable of digitigrade bipedal progression. You evidently missed my paper in Ichnos 2000. Peters D., 2000, Description and interpretation of interphalangeal lines in tetrapods. Ichnos 7, 11–41 which covers all your issues with bipedality and trackways.
Well, unless you found trackways _of *Eudimorphodon*_, interphalangeal lines won't help you finding out whether the beast was capable of sustaining digitigrade bipedal locomotion for any serious amount of time. I can walk and run digitigradely; I just can't sustain it for more than a few minutes because it hurts...