Did you power everything off and on again.. in the right order.. restart modem.. then TC then all the wireless extenders.. then clients like printer.
Check that the printer actually received an IP from the TC.. most printers will how it on LCD display or print out the test page.
Ping the printer IP from the computer.. does that work?? If it fails you cannot print nor will the printer show up so start again.
Do the printer setup via the WPS again.. it must get an IP and must be pingable..
It could fail to work once the system has been up for an hour due to lousy DNS discovery in later Mac OS.
Delete the printer in the computer and rediscover it..
Tell me the full setup.. is the TC working as main router for the network or is it bridged?