given that handy stroboscope can also check translational vibration of parts, is it a substitute for a test that can be done by accelerometer for stationary vibrating equipment?
No. Strobes are useful for what they can do, but they are not substitutes for accelerometers.
A strobe can give you a "picture", but it doesn't measure anything except maybe frequency. It doesn't measure amplitude, harmonic content of the vibration, etc.
Also a strobe is only useful for amplitudes which are big enough to see. Accelerometers can measure high frequency vibrations with amplitudes of micrometers or smaller.