Just want to make sure I'm understanding this: the receptacle for bodily wastes is a "little house"?
Although toilets are nowadays indoors, in the age before plumbing the toilet was sometimes in a liitle shed outside, at the end of the garden perhaps. Hence 'the little house', which is the term which has stuck.
toiled is also used, but doesn't really need learning. A variation which you sometimes hear in some areas is y lle chwech ('the sweet place').
Well, it used to be 'outhouses' in English and I've heard that as a joking euphemism for the toilet ("oop, gotta stop by the outhouse before we hit the road!") so I suppose it's not all too different.
Although silly euphemisms about lavatories are my favorite. Like the German wohin der Kaiser von China allein geht ("where the Emperor of China goes alone"). And now, the Welsh "sweet place."
(ETA: Wait, isn't chwech "six"? So "the six place"?)
chwech is 'six'.
It is also an old (Middle Welsh to Early Modern Welsh chwech/chweg) word for 'sweet/pleasant/?sweet-smelling'.