Seconded!
Either 1) use the English plural, or 2) use the correct foreign plural (and then only if it's recognisable).
"Bonus" is an English word. It does not mean the same thing as the Latin word it is derived from. It has no other acceptable plural.
My pet hates:
1) octopus. "Correct" plural is "octopodes". "Octopuses" is to be preferred.
2) platypus. Similarly, "platypodes" or "platypuses"
3) omnibus. It's already in the plural!
4) data, criteria. Once again, already plural.
5) mongoose. They ain't geese, they're mongooses.