What's the difference between "yno" and "yna"? Is it a north/south thing again?
Nothing to do with dialects.
yno is usually used to mean 'there' when 'there' is a long way away, or out of sight. yna is somewhere nearer at hand, generally. yna can also be used to indicate time, which yno cannnot.
- Wyt ti'n nabod Prague? Ydw, es i yno ar wyliau'r llynedd (Yes, I went there on holiday last year)
- Gwnes i aros yno am wythnos, ac yna es i i Berlin (I stayed there for a week and and then I went to Berlin)