Something about these makes me wonder about the context, though I'm pretty certain the first one has something or everything to do with the Fade. XD
After listening to an hour+ of Welsh accents last night I'd giggle if he sang a little ditty and it became less and less intelligible as it went on
In several of the interviews I listened to the speaker's accent became heavier the longer they spoke and they'd start randomly slipping into Welsh, it was pretty cute 
Edit: It wouldn't be too out there for Solas to know/sing an interesting song or two. He spends his time "searching for memories and knowledge that have been lost for ages" so I'm sure he's come across a song or two sifting through other peoples' experiences 
Catching him singing something could potentially be a very interesting way to get to know him better.
Well, stick him with Sera and Iron Bull and what if he starts singing dirty lymericks? I mean, that would be hilarious and surprising, since it's probably not what we're going to expect from Solas...
That would make for some amazing banter, particularly if he sang in an old language he heard in the Fade. A little while later, and Sera and Bull are trying to pry a translation out of him.