Diolch Jeanne! I really enjoyed your company and I’m always happy to chat in Welsh with anyone who wants to stay, though the days are a little more restricted now as I have a lodger who comes every week for work and stays Monday night to Thursday morning. Weekends are generally available though for quick visits.
Deborah 
I stayed at Rhydydefaid Farm (https://www.rhydydefaid.co.uk/) in Frongoch for a few nights in July 2019. The owner, Mrs Davies, is a Welsh speaker – in fact we didn’t really speak English at all except to the other guests (she must be patient!). The accommodation was nice and the breakfasts were great; I’d definitely recommend it.
It is no longer possible to search the Best of Wales accommodation for Welsh speaking owners. I have emailed them and this was their response. Hopefully they will reinstate this feature.
**Our website was recently updated and it appears that the Welsh-speaking owner filter was removed. *
*** you let us know the area of Wales you would like to stay, we can inform you which cottages in that area have Welsh-speaking owners. I have forwarded your email to the marketing department to ask them to review this.
Update of response from Best of Wales site below, looks like the ‘Welsh speaking host’ filter will be restored!
Thank you for your email. I passed on your comments to the marketing department and hopefully the filter for Welsh-speaking owners should be restored very soon. As a Welsh speaker myself, I am very grateful to you for pointing this out and bringing our attention to the omission.
Diolch yn fawr, @Howard. I’ll certainly keep your place in mind for future. For this holiday, though, we need to stay up north around Conwy/Llandudno area to be close to the fam.
What I would really like to do is stay and spend all weekend talking with a native Welsh speaker, preferably in mid/North Wales. I think it would be too expensive for me though. Does anyone have any ideas?