for corner carry as said trial 8 would help the time is strict it requires 1 meter for the 3rd ex moonslasher.strict time is to connect the 2nd moonslasher after the 1st sabre.train help.considering if u have meter u can start the corner carry with ex sabre which give u more time to dc in the moonslasher. this combo requires 2 bars cause u have to do the ex version of the 3rd moonslasher, by the way the corner carry is granted and it is pretty easy to do.
for instant overheads , yeah they r too difficult to hitconfirm, they r more a ' choice ' . playing using high low mixups and baiting the wrong block can open the way for an instant overhead. i find it easily to do just a qcf buffered while doing any other move and then just up and then hcfb u have all the time to do the moves not like an unique movement thanks to the buffering time of this game. or if u feel better to do an unique movement maybe try to change the D instant overhead with the A version.if u jump forward u r doing it too fast, try to work on the time of up jump and remember this game give u all the time u need