I've helped a couple of guy with different Kyosho Ceessnas. one was the smaller (I believe discontinued) appx 38 to 43 inch span 3 channel
The other ws the one you have.
Yours is better.
Really... the hinge line as is will be OK... There is a way to SLIGHTLY improve it by tucking a second layer of tape into the beveled area, so the 2 layers of tape stick to each other in the hinge line. This type of hinge is very durable and flexible (if the tape itself is not too stiff.. cheap clear packing tape is ideal)
Ther is a small amount of drag from that bevel... yes. There is also a slight amount of turbulence over the right side of the rudder from it... It would be a problem if the plane could exceed 50 mph.... but that plane would rip itself apart at that speed. (ain't broke... on't fix it)
The control horn is just a bit back on your rudder from ideal location... its not off far enough tobe worth moving it. You will have slightly more throw to the left than right is the only effect you will see. The difference will be small enough, that on that model you can ignore it. (some things just aren't worth worrying about)