No command allowing someone to TP into an area (/home, /tpa and the other staff commands I've tried) will let someone teleport into a sealed area (Sealing is necessary to make the air inside breathable). I think this is because the "air" has been replaced with tile.breatheableAir.name block id 177 from galacticraft. Would it be possible to get that block added to a list of tiles that can be teleported into? (I think @SirWill is the right person to tag) although im sure a certain person will correct me if not
The way essentials works is to run a code that searches for safe blocks to teleport to, sadly this means that there isnt actually a config option or a list that we can add those blocks to. Maybe a @Developer might be able to do something though
seen + tppos might work ? It could also be that enabling gamemode or god lets you bypass the search for a safe location