so how does everyday life work for them now? can they still see normally or do they only see from the other's perspective? if the latter, do they swap eyes when they need to be apart or do they just never part anymore?

As stated here: http://dynasty-scans.com/chapters/my_eyeballs_told_me_to_dedicate_everything_i_have_to_you_last_part#5, it seems it only happens sometimes.

but if it only happens sometimes, does that mean they are blind most of the time?

You've got something wrong. The uncovered Eye is the eye they can see normally with and the other person can look thru it with there covered eye, thats why its one left and one right uncovered and covered