More than just a matt undercoat, yes alright. But still looks ad hoc and not quite fitting in with the rest of what they had.
A pic here of a brand new 121 being craned off the boat, minus bogies and already carrying snails, numerals and wasp stripes. Perhaps sets of transfers were either sent over or sourced and made up Stateside.
https://upload.wikimedia.org/wikipedia/commons/a/ac/GM_diesel_locomotive_B124_being_unloaded_from_a_ship_at_the_North_Wall_in_Dublin.jpg
(bit hard to see, needs a little enlargement and they can be made out)
Don't know about if the rail side of CIE took cues from the bus side, apart from the outset where the first CIE logo and livery was a variation of the DUTC scheme.