I'm guessing taigh-osta is only used if it's a place you can staigh the night, but I'm not a reliable source. I mainly think this because osta reminds me of hostel, but might be unrelated.
another thread went into this. seems to be a loan from the english 'change', coming from the days when you'd change horses on a journey. Taigh-seinnse, then, is a change-house, or a travel inn.
It's also possible that 'seinnse' < 'seinn' (singing), as Wiktionary says. 'House of singing.' However, the morphology doesn't look right. You'd expect 'taigh seinne', I guess.