Looks like the TF series does not have input delay per channel (their higher end boards do) so I would look to run the mics to a matrix (don’t route to the LR buss), delay the matrix and route the matrix to the main LR buss.
Edit: Looks like you might be able to route right to the FX busses post fader and they have a output delay FX so it could be very simple.
Input post fader (not routed to ST) → FX 1 “output delay” → FX 1 RTN → ST (main) buss