I mean it was 600,000 lines of Zig prior to the rewrite yea? If we say that a team is ~6 people, that's 100,000 lines each to read through and translate. Assuming 250 working days in a year, that's 400 lines of code you just need to read every day, let alone the Rust you need to be writing (approximately another 400 lines).
Add to that overhead for planning and coordination... I actually think a year for a team might be an underestimate.