The current transformer is not a problem. From one model/brand to another you may need to change the Burden resistor (here R21) and do some calibration. No real problem.

Thew whole design, in general, seems nice. There enough insultaion to be safe. The harder part will be the software.. as always

I can't confirm the CS5460 performance as i never used it before. But it seems nice.

There's no problem to use the unregulated power supply for you LCD backlight. I do it often here too. an extra 7805 (or else) regulator could also be use instead of a resistor... it's up to you. HPWM control is also another idea.

Usually the diode across a voltage regulator is needed IF the external world COULD be disconnected from the PSU... e.g. bench PSU... It's a good idea but not a must in most case.