If my design takes Cyclone V E 5cefa, but doesn't use hard memory controllers, is it interchangeable with the 5ceba of the same die and package size?
Yes, You can migrate to 5CEBA if device densities in the same package option if the devices have the same dedicated pins, configuration pins, and power pins.
Compare the pinout files.
And check page 18/ figure 17 from below link.
Let me know if this has helped resolve the issue you are facing or if you need any further assistance.
Thank you, Anand,
I did check pin-for-pin between the two devices I am evaluating. The primary use pins are identical between the "F" and "B" versions. The "F" version has some pins with secondary use for HMC, but since all these pins have primary use as I/Os, I conclude the two versions with same die size and package are interchangeable (absent HMC use).