max+plus2 advanced synthesis error message

The code compiles correctly in Quartus. I don't see a problem, that can be expected to cause problems in max+plus2.

Apart from this point, som design details seems questionable in the code:

- why are counting input events mutual exlusive (using else if).

- do you intend to count 0 to 10, as the code does, or 0 to 9?

- do you want to count negative edges or sample low state?

- assuming the inputs are unrelated to CLK, synchronizing would be required to avoid wrong counting