Why is it a backside 180 nosegrind but a backside 180 switch manual?
it's kinda weird... my best guess:
bs 180 nosegrind=similar concept to bs bigspin noseslides or boardslides actually more being shove it nose/boardslides to fakie. the skater does a bs 180 with a nosegrind in the middle. trick name is not determined by orientation of the grind in this case, but in order of total body rotation of the ollie/flip trick and the trick done after the catch or after the initial trick has completed 50% progress or more. the grinds name is determined by what it would look like without the rotation in mind, so as if done regs.
this is one example of an alternate naming convention compared to just composite trick names that follow a dogmatic school of trick plus this way trick plus this way out trick, in favor of a more elegant and wholistic approach. it makes sense if you see the bs 180 more as beginning and also end to the trick instead of the two tricks as a linear sequence. the trick begins with a bs 180 and ends with fulfilling the bs 180, with the nosegrind happening in the middle.
my guess on why the sw manual isnt a fakie nosemanny would be that you can only get into a fakie nosemanny coming in fakie from the start. if you 180 into the same manual it's switch since if you popped out it would be a switch trick. with a bs 180 fakie manual it's fakie because if you would need to pop out like a fakie trick.
EDIT: the logic has flaws, like how fit fakie nosegrinds into this? so what are the rules to go fakie (nose-)manual(and grind)?
i would say there's two ways.
you have to approach fakie and either get straight on or 360.
you approach normally and rotate into a position that forces you to disengage from the manual in actual fakie stance, and only traditional fakie counts, meaning the only way to end up in any sort of fakie coming from regs is a fakie manual done on the truck you popped off, too. there just is no fakie nosemanual initiated by a 180 coming from regs.
similarly, when you nollie 180 into a sw manual, why is that not a fakie nose manny? because if you mirrored it and did it from fakie, like starting with a half cab, you end up in a regular manual, not a sw fakie nosemanual(lol). hence when mirrored sw stance it's also a manual, but switch.