Well, first I'll lay out what are the different timelines and such in Fate works (even if you've all heard this a million times over) for a better understanding of my point.
Zero ---> Stay Night (however, there are some glaring inconsistencies between them and so the timeline does not fully match, but it is close enough for scaling to work) ---> Hollow Ataraxia (again, similar faults as to the first but close enough for scaling to work)
Apocrypha
Extra/CCC (takes place on the Moon Cell, so scaling doesn't really work well here for the most part)
Prototype
Prototype Fragments (Scaling for Proto Arthur may work from Prototype, but only for Arthur)
Strange Fake
Grand Order (though it does visit or touch on some of the timelines here like SN and alternate version of Zero, as well as parts of KnK here and there)
So based on this, it's difficult to scale between most Grail Wars since they have quite a few differences based on differing timelines and such. However, one can still scale some characters based on reputation (Karna, Arjuna and so on) or if you find the difference between the Servant/ their containers to be minimal (Proto Arthur to other Fragments characters, possibly SN to other verses including Apo and GO). This all comes down to how one interprets the situation as the type of containers don't really change through out the various works save for Extra/CCC.
For Strange Fake however, I did find some quotes regarding lightning speed, which are here:
https://vsbattles.com/vsbattles/303803 towards the end of the thread
If you wish, you could make calcs based on that.