When listening to pop tunes I prefer constant music tempo, and so
I usually diminish the paper speed as it plays. Otherwise the speed
increase is noticeable, with both electric motor drive and with
well-governed air motor drive.
Dance bands try to play at constant tempo, so I assume that the
pop music roll editors also intended constant tempo. Most 5- and
10-tune Wurlitzer rolls are continuously compensated so that they
play constant beats-per-minute.
When Wayne Stahnke transcribed Ampico rolls for the IMI Cassette
Converter (25 years ago!) he flagged the data file so that playback
could be at "constant paper speed" for pop tunes and some early
classical tunes. If you decide to compensate the pop songs to
constant metronome beat you can cite a precedent. ;)