The question is - does accelerando used in parts with different tempo? How to rhythmically align them after that / during that? (Without accelerando it would be enough to keep parts tempo at some fixed ratio)
S1 : e - e - e - e - e - e - e [accel from 60 to 120 bpm] S2 : q - q - q - q t0 t1=??
where S1,S2 - stave 1,2; e - eight note; q - quarter
How to properly calculate start time and duration time of each beat during accelerando? [It is not that important if song have only one tempo, because all beats will have same timings regardless of how we calculate accelerando]