About the EVF lag and the R5.
A sprinter does 100m in 10s, 10m in 1s. If your EVF framerate is 30fps, the athlete will pass 33 cm during the frame update so your view will always be lagging up to 33cm behind (it can be much less depending on several factors, including the shooting angle).
at 60fps it'll be up to 16cm, 120fps -> 8cm etc. I highly doubt the R5's EVF will do 120fps.
However the human reaction time to random events is about 0.1-0.2s which is much longer than the frame duration even at 30fps. With the sprinter in the example above, 0.1s translates to 1m. A trained photographer can predict say a climax of a jump and hit the button upfront, but they'd normally use continuous shooting instead.
Therefore, the EVF lag mostly matters when something unpredictable happens so that the very first frame of the continuous sequence isn't taken too late, or in cases when continuous shooting isn't possible/practical.
That will be important for the future R1 line, but not so important for the R5 I guess. Accredited olympics photogs won't use the R5 anyway, and for the rest, EVF or OVF won't make a big difference, will it?