I’ve marked with an * any phrases that are Scottish or Irish Gaelic in origin, rather than made up for Fade Rift.

A ghlaoic (air do chasan)* - You (damn) fool.

Breò-chual de nathair-sgiathach - Dragon’s pyre; more literally pyre of dragons.

Tachd air té fòthannan - Choke on a thistle.

Faod leòmach faoileag gearr do sùilean - May vain seagulls take your eyes.

Sibh sealbhaich an loinn de raoiteach gibealach - You have the grace of a drunk octopus.

Briseadh agus brú ar do chnámha* - A breaking and crushing on your bones.

Trasna ort féin* - Go across yourself. (Although its general meaning seems to be a bit more explicit than that.)

Chan eil de dh'eanchainn annad na bheireadh blas an dàthaidh bho do cheann* - You haven't the brains God gave a flea! (fig. “Maker” for FR, obv.)

The following phrases are (I think?) originally found in Irish Gaelic, but I couldn’t find translations online. They’ve been hideously translated with Scottish Gaelic.

Faod do buntàta cinnich cosail seanganach air a’ cuiseag - May your potatoes grow like ants on the stalk. (Originally: may your spuds be like rosary-beads on the stalk.)

Faod thu faigh for air sgaoth sheillean  ach ionndrainn a’ mil-seillein - May you find the bees but miss the honey.

Faod thu leagh far a’ cruinne-cé  cosail sneachd far clais - May you melt off the world like snow off a ditch.

(Thu is the singular form of ‘you,’ but plural would be sibh. Of course, to be more insulting staying with the singular for a plural instance would probably work.)