Aderyn - this is just the welsh word for bird, it isn't a name. Deryn is a bit like Darren.
If you use a welsh name, make sure you and your parner can pronounce it.
Some welsh letter combinations are very difficult if you don't speak welsh, including
ei (e.g Eira, Eifion)
eu (e.g. Euros, Lleucu)
ae (e.g. Aeron)
ir (e.g. Mair, Meinir)
uw (e.g. Huw)
wy (e.g. Dwynwen, Mathonwy)
si (e.g. Siân, Siwan, Siôn)
ngh (e.g.Angharad)
yw (e.g Llywela, Hywel)
Rh, Th, Ch, Ll, Ng, Dd, Ph, Ff are single letters in Welsh.
An advantage of the Spanish - Welsh combinations is that both languages emphasise the penultimate syllable.
I would go for a name that has a nice meaning and is phonetic in both languages.
Lloer (moon) - not a name, not nice, and unprounceable if not welsh.
Alaw (air) - Melody
Grug (heather) - never seen or heard it used as a nameand unprounceable if not welsh.
Celyn (holly) - boy's name
Haf (Summer) - difficult to
Enfys (rainbiw) Rainbow. Terrible as a name unless your surname is Presley.