[Sawrock]

The bonus +12 for evasion is likely not working for Sarashi Gi; however, the bonus +12 for critical is. This was tested by having two of the same weapon (Bear Claws) with the same material (Galdric) equipped at once with a Sarashi Gi (Breezecloth) equipped, and then switching over to a Cloak of Many Colors (Rubber); while the Sarashi Gi has 23 modified evade (not including its ability), the Cloak of Many Colors has 20 modified evade, and it indeed did show a difference of 3 evade in the evade section of my player stats. It should've instead have been 15 difference due to the +12 evade from Sarashi Gi's effect.

Edit: After testing it in battle, it merely appears to be a display bug in the stat screen.

[Neus]

It's possible that it doesn't display on the stats screen like a few things which check to see if you're actively in a battle to avoid some overhead.

[Sawrock]

Then could the bonus critical be hidden as well?

[Neus]

Could be as in are you requesting it to be hidden or could be as in 'is it possible it is'?

[Sawrock]

Requesting it to be hidden so it matches how the evade is hidden.