I know that critical rate and hit rate are two different things but it's kinda weird this situation.
Are you sure? Because if so, you should see the "prohibition sign" on the number, as for magical damages.
Hmm it can be supposed that the enemy's hit rate it's lower because the sisters are close to each other, giving each other bonus... ? edit: it could be. I find out that when 2 "good friends" are close, they get bonus as you said and I can see them with an increase to hit rate with a orange extensions of the hit rate bar, for example.
2x strikes not visible can be indeed a bug otherwise the two lower bars under the HPs wouldn't be there. Infact 13atk-6def=7dmg, 7dmg*2strikes=14 total damage and here we got the exact prevision showed.
I cut the images because the down screen was usless. The stats in this action to know are only atk and def. It's the same turn in the same action of my pegasus rider. The speed stat of the enemy was higher so the double strikes are ok.