Not sure if the 'Only Left Speaker' bit has been fixed but perhaps just check the correct 'Master' connections have been made, when I first added my 218 I initially made this small error with them the wrong way around and had a similar result.

Regarding the 210, 218 etc. Another option to try which is very similar to what I do is to not have the 210 connected to the G65 at all. Go G65 -> 218 - SE's (via SpeakerLink). Connect the 210 to the 218 via Digital Coax and configure the 218 to switch inputs based on your selection on the G65. This works good for me and keeps the streamer 2 channel MQA stuff away from the processor however since I dont have a 5 channel setup Im not sure how the combination of the speakerlink in the 218 works alongside the other speakerlink outputs from the G65. Id assume it 'should' work but you'd have to test.

Good luck.

Meridian 218, 5200SE, Auralic Aries G1, Panasonic DP-UB9000