I2C slave compatible with SMBus protocol?
That depends on how much of I2C protocol is implemented in your Arria controller. If it is just reporting the "events" to the program (like "STOP detected", "START detected", "ACK received", "Address received", etc.), then most probably you will be able to implement most of the SMBus, except for maybe ARP which requires, AFAIR, responding to a broadcast address (which your controller may not have support for). The other concern is timeouts. SMBus have stricter timeouts, especially in regard to clock stretching.
Compatibility would highly depend on the extent to which the master uses the SMBus protocol and expects conformance.

On the other hand, if your Arria provides a higher level abstraction (like "Send I2C byte"), then it most probably will be a show-stopper.

If you have any evaluation board for your Arria 10 FPGA, I would recommend testing the concept using that board before you go with this chip for design and production.