Astudiaethe Celtaidd, an Léann Ceilteach...

This can confuse people a lot when they're learning verbs, especially when they're taught with a mix of the dialects but each dialect is quite internally consistent with it.

This also applies to -idh as slender dh and slender gh have merged in every dialect.

In Connacht these are entirely silent, so in an unstressed syllable they're just pronounced like a schwa, a neutral vowel.

Cheannaigh (bought) -> Cheanna

Bhailigh (collected) -> Bhaile

Cuirfidh (will put) -> Cuirhe

Samhraidh (of summer) -> Samhra

In Ulster and Munster, the pronounciation is also a schwa when it is a verb form before a pronoun:

Cheannaigh sé (He bought) -> Cheanna sé

Cuirfidh sé (He will put) -> Cuirhe sé

But, if it isn't before a pronoun then it is pronounced like 'í' in Ulster and like 'ig' in Munster.

Cheannaigh Seán -> Cheannaí Seán (Ulster), Cheannaig Seán (Munster)

Nigh (Wash) -> Ní (Ulster), Nig (Munster)

Why is there so much art of knights fighting giant snails in marginalia?

Some think the snail (which carries its house on its back and works hard) represented the peasant class, while the knight represented the oppressive aristocracy. It can also represent a cowardly knight that acts brave but isn’t.

Like in English the phrase 'Goodbye' comes from 'god be with you', but nobody views it as a christian phrase, because it's come to be seen as its own thing (obviously confusion with Goodnight etc. has made it less obvious in the spelling)

Similarly a lot of people would say things in English like 'for god's sake' or 'bless you' when someone sneezes, moreso because they are phrases than because they believe it.