Position of leds in the RX/TX portion of an arduino compatible
The RX LED (TXD pin) is going to blink in either location but will reduce the signal level to the CH340 if moved west of R9. this may render the CH340 unable to receive. It may be possible to use the TX-enable input to the RS485 to control which RX led illuminates.

the TX LED (RXD pin) in it's present location is reducing the signal level to the CPU as it forms a voltage divider with R8. It will probably blink brighter if moved west of R8, and the CPU will see a stronger serial signal. probably other signals on the RXD pin will not cause it to blink.