I can not find anything about 100Mbit/s TX & 100Mbit/s RX in the spects.
is common sense in networking
Full-duplex data transmission means that data can be transmitted in both directions on a signal carrier at the same time. For example, on a local area network with a technology that has full-duplex transmission, one workstation can be sending data on the line while another workstation is receiving data. Full-duplex transmission necessarily implies a bidirectional line (one that can move data in both directions).
Full Duplex means that if your switch port is 100 mbps - you can upload 100 mbps and download 100 mbps at the same time
Effectively your I/O throughput is 200 mbps
Duplex means two way communication simulataneously
so mikrotik can do 200mbps over wireless, 100 upload+100 download.