"Dych chi'n hoffi'r tylluan?"

Translation: Do you like the owl?

[Lundgren8]

Should it not be y dylluan since tylluan is feminine?

[nebynAmlwch]

It should be 'y dylluan' as it is a feminine noun in the singular after y fannod.

[NicDafis]

Yep. Reported, in case neither of you did.

[Guinevere18]

In case it is Duo we are talking about, the answer is definitively yes :-D