Attributively used adjectives normally take the ending -e. That is true here too.

Attributively used adjectives usually take the ending -e. That is the case here, too.

When the noun remains unmentioned or is replaced by ‘ien’, the adjective usually takes the -en ending.

Attributively used adjectives usually take the ending -e. That is the case here, too.

Attributively used adjectives usually take the ending -e. That is the case here, too.
Notice that ‘myn âlde pake’ is not necessarily wrong, but in Frisian it is more common to use the plural form of the possessive pronoun with family members.
Also notice that ‘âlde pake’ may be both ‘old grandfather’ and ‘greatgrandfather’ (so: your parent’s grandfather).

‘Fereale’ already ends in -e, so no extra -e is added.

‘Beer’ has the it-gender. Because there is no determiner, the adjective remains uninflected.

‘Curious’ is ‘nijsgjirrich’. The adjective is used predicatively here (not right before the noun it belongs to), so it remains uninflected.
Notice the different word orders in English and Frisian: the uninflected verb comes at the end in Frisian.
Also notice that ‘nijsgjirrich’ also means ‘interesting’. The Frisian phrase is therefore ambiguous.

Attributively used adjectives usually take the ending -e. That is the case here, too.