。。
Hmm. Whether one can actually trust those words, I'm not so sure.
Literal
Well-then. Those words [to-に] trust [object-を] placing good thing [I-wonder-やら].
さて opens a contemplative pause — not the 'well then, let's get started' usage but the reflective 'hmm, now then.' 信を置く ('place trust in') is a literary set phrase. ~てよいものやら is an indirect question expressing doubt: 'whether it's okay to' + やら signaling uncertainty. The trailing やら leaves the doubt unresolved, a common Japanese strategy for expressing skepticism without committing to a negative judgment.