Mind this is PHY side, which is driving a CT winding. The two traces act as stubs against each other, so their lengths should be kept as short as practical, and lengths matched.
What level Ethernet? At 100BASE-T, a few nanoseconds of imbalance would be big deal. That's almost nothing to worry about on a PCB. 1000BASE-T needs to be tighter, but even simply within a few mm is more than good enough!
Signal quality really only matters in the extreme, near maximum length, with poorly matched or corroded cables and connectors, poorly made splices, etc. For casual runs say in the 10s of m long, the built in signal quality enhancements of 1000BASE-T more than make up for any of that.
Ethernet can literally run on wet string (specifically, brine soaked), albeit at 10BASE-T and only to a fraction of its nominal range. You can't do much wrong to get any connection. How good of a connection, and over what distance, is what actually matters.
Tim