Have the devs responding to you or about this topic anywhere else?

For now there has only been this emtpy space concerning this topic. Meaning: No!

I agree with the second point, altho the first one doesn't bother me very much. Do you know if happiness modifiers from planets with sanctuaries have any impact on the nexus happiness? 

 If not, that could be a solution. At least making players think about what the downsides of going for that extra gas single planet system are. 

No, Sanctuaries do not affect the Nexus at all in terms of approval. The only affect Sanctuaries have on approval is overcolonization which is easily mitigated by improvements in the Nexus. This is intentional because it allows the Umbral Choir to be widespread and capitalize on Sleepers. If mass expansion was dissuaded then the Umbral Choir loses one of it's primary design mechanics. 

As to the second point, it's a weird situation honestly. The only way to really fix it would be to make Umbral Choir heroes not show up on the Academy (which would be another problem altogether) or to not show the location of the governor of the Nexus just list their name, levels and so on. 

At least the second issue has now been noted here. I guess the best solution for it, might be to just show "assigned to a special node" or something  along those lines in the Academy.

Hello,

Sorry we didn't respond, we've actually seen the issue :). It's true that the UC can currently circumvent overcolonziation a bit too easily, we'll look into solutions. The second one is a bug, it shouldn't show the UC system location.