The original AC one should be this one:
https://mikrotik.com/product/up1302c_12
with 10.8 A @12 V it is much more powerful than the 7 A @12V of the PW48V-12V85W, though the 7x12=84 W (or 85 ) are just the same as the max 83W of the CCR 2116:
https://mikrotik.com/product/ccr2116_12 ... ifications
Hard to say if the AC power supply is actually oversized and the 48 V one is just right.

Since the 2116 is not a cheap, entry level router, I presume that it will be used in a professional environment, I would ask for an official statement by Mikrotik support and/or local distributor as replacing the PSU with another one might affect the warranty and/or safety of the device.