Can more BL5340 modules work in parallel for channel expansion?

Yes, every module can handle 4 channels. Additional modules may be used for additional channels. But there are RF interference concerns with the higher number of transmitters from additional modules. Possible to coordinate the modules so they do not interfere but may need to consider something more sophisticated to coordinate the devices to maximize the 2.4GHz spectrum.

Note Ezurio (formerly Laird Connectivity) maintains a partnership with Packetcraft for LE Audio SW Solution.

https://www.packetcraft.com/