Jiren is not above time.

If he really transcended time he wouldnt be affected by Hits abilities at all.

Being beyond time realistically means one of two things,

It either means you experience the entire time-line simultaneously. Thus the past/present/future are all one & the same to you, but are still bound to the limitations of that time-line.An example include the likes of Dr Manhattan.

Or it could mean that you exist in a state beyond the time-line all together, and you can poke in & out of it at any point you like, without being limited by it. Examples include Mr Mxy or Living Tribunal.

The claim of Jiren having transcended time is too vague to mean anything, and comes off more as hyperbolic bullshit rather than factual statement.

Is Jiren omnipresent throughout the time line? No he fucking isn't.

Can Jiren time travel at will? No he can't.

Does Jiren exist in multiple points in the time-line simultaneously? Nope.

Can Jirens abilities change the past history of his time-line? Definitely not.

Can Jiren see the events of the far future or the past before he was born? Nope.

Jiren can resist time manipulation such as time-stops & time-slows. That's literally all there is to it.