well i don't think that the covenant separatists had any engineersEngineers were the more "I'm only going to stick to my ship" type of alien. Not to mention that many of them were wiped out.
To add; its stated that the UNSC now holds a large quantity of Engineers due to the captureing of Covenant technology, etc. So humanity pocesses more than any other species now.
DOESNT MAKE MUCH SENSE
1 IT SAIS THERE LOSING
2 IT SAIS THERE WINNING
id go with losing in the beginning then they started winning cause the brutes started fighting each other so the grunts,hunters and the engineers camme to the elites side
In Glasslands it states that most engineers fled, Likely to nearby Forrunner instalations