It certainly is possible. I've done it to various patches for various purposes. A very useful Synchron Player ability!
• In Sychron Player's MIx tab, to route any given channel strip to a different output of the Synchron Player plugin, set the strip's "Output" field (immediately above the output channel name) in order to route it to any one of the Synchron Player's available audio outputs, as you require. This "Output" field offers a pop menu listing "1 (Stereo)", 2 (Stereo)", etc. You can also rename the strip by right-clicking on the field at the very bottom of the strip and selecting "Rename" in the pop menu.
• In the Edit tab, select the patch you're routing, then look in Options/Mixer Output setting to ensure that the patch is routed to the strip(s) you require, and whose output(s) you've routed as described above. (I mention multiple routings here because for this setting you're offered a patch-to-microphone routing matrix in some Synchron libraries; but this may not be offered in SE libraries, I'm not sure.)
• As needed, you can - as you've noticed - click on one of the "+" symbols on the right of the mixer to create either a new 'microphone' channel strip (the upper + sign), or a new aux channel strip (lower +); then assign the patch input and strip output routings as described above. Note that it's not possible to route a patch directly to an aux channel strip.