Lets say there is T4 mod with roll gap 100-200% physical damage and lets say my T4 roll is 199% if i use glyph of order and it will upgrade it to T5 and for example T5 roll gap 201-300% will i guaranteed roll 299% becuz i used glyph of order?
Just think about the min roll being 0% and the maximum roll being 100%.
Whatever value you rolled will stay the same % roll.
To give a more concrete example:
2-handed melee weapon with a T4 flat melee damage prefix. (Rolls 29-37; 29 = 0%, 33 = 50%, 37 = 100%)
Lets assume you rolled 33 on T4, which is 50%, the 50% roll would stay at 50% leading to a 43 roll on T5 (38-48)
With a 37 roll on T4, which is 100%, the T5 affix would be rolled 48.
Attributes, probably not since those don’t tend to have a particularly big range (if at all), but yes, if you have a very high roll on a t3/4 & want to upgrade it a glyph of order would probably be useful.
Personally I almost never use it, way less than I probably should.
It is so unfrequent for it to be useful that in the rare occasions where it would apply I still end up using a gliph of hope.