Speakers of Irish live in a largely English-speaking environment, and a natural consequence is that English clichés tend to infiltrate their speech. This is incidentally why you should read literature by native speakers – sooner or later you will find a good translation there.
Years ago I made this list of better Irish translations for some English expressions which too often are rendered into Irish word for word or which might be found difficult.
* To start with, all in good time. Back in the good old days I proposed glacaimis an gnoithe i ndiaidh a chéile – I am not sure where I found it – it is possible Ciarán Ó Duibhin gave it to me on Gaelic-L, but it is also thinkable that I found it in a folklore volume and have forgotten the exact details. Today, of course, I would write it glacaimis an gnó i ndiaidh a chéile – gnoithe is commonly used for rendering the Ulster pronunciation, but gnó is standard Irish.
* The second example in my list is better less, but better. To tell the truth, it is not exactly an English cliché, but an English rendition of a Russian phrase relevant to the early history of the Soviet Union. As you know, I studied Russian before Irish, and one of my ambitions has always been to make Russian and East European culture accessible in Irish translation. This particular phrase fascinated me for a long time because it felt so difficult to translate into Irish. One day though I found an idiom that catches the sense exactly: is fearr beagán go maith ná mórán go holc.
* There is an old joke about two men about to be shot by a despotic regime. One of them spits at the firing squad as a last gesture of defiance. The other says to him, shivering with fear: “Please Bill, don’t get us into trouble.” The idiomatic translation for this would be: ná tarraing seantithe anuas orainn. It might be narrowly Ulster Irish, but that is fine for me. (As far as I remember, it is mentioned in several authoritative sources, notably in Leaslaoi Lúcás’s Ros Goill vocabulary.)
* In English, the personification of death is known as the grim reaper, and he is depicted as a skeleton wearing some sort of long robe and carrying a scythe and an hourglass. The only expression for personified death I have found in native literature is an rógaire bás, ‘death, the rogue’, which is what the Islandman, Tomás Ó Criomhthain, used in his autobiography at least once.
* I have often been asked, how you say in Irish have-nots and have-lots. No problem. It’s na daoine ar an ngannchuid agus na daoine ar an anchuid. For na daoine read na daoiní, and for ar an ngannchuid read ar an ghannchuid, if you are from Ulster.
* For help yourself! at the dinner table, I recommend tarraing ort! or if you are speaking to several people, tarraingígí oraibh! Note though that focloir.ie has other recommendations, which may be better.
* When something is in good working order, the best translation in my opinion is i ngléas, although this basically means that it is electrically or mechanically connected. If I was asked to translate into Irish a story about First World War pilots, I would choose – I ngléas? – I ngléas! as the Irish translation for – Contact? – Contact!
* Is Pope Catholic? This is usually translated as An dtuigeann an Pápa Laidin? (“Does Pope understand Latin?”)
* It came true. Well, the word-for-word translation is tháinig sé fíor, and you do see it in the Gaeltacht literature, but I’d prefer to add the word isteach: tháinig sé isteach fíor. This is what Séamus Ó Grianna used, and his word is gospel for me.
* It‘s getting late. It is not wrong to use tá sé ag éirí deireanach, but here are some alternatives from Gaeltacht literature:
tá sé ag druidim chun deireanais (actually, druidiúint chun deireanais is what I found in Cape Clear Irish, but druidim is the standard form)
tá an deireanaí ag teacht
tá an lá mall
tá sé mall sa lá
tá sé ag dul anonn sa lá
tá sé ag teannadh amach sa lá
* Let bygones be bygones – that would be fág na seanchairteacha.
* Let sleeping dogs lie is ná bain fuil as seancholm; the thought can also be expressed with is furasta seanaibhleoga a lasadh ‘it is easy to rekindle old embers‘
* Old Nick, the devil, is an Seanbhuachaill (the old boy) or an Fear Dubh – the black man. Note that dubh usually means black-haired, not black as in Africa. Dark-skinned people are in Irish said to be gorm, i.e. blue.
* Perk up, old pal would be something like breabhsaigh ort, a mhac. Note the verb breabhsaigh/breabhsú.
* Rule out in the sense of excluding a possibility is rud a bhaint as margadh. I don’t know if this is at all found in Ó Dónaill‘s dictionary, but I picked it up from Máirtín Ó Cadhain‘s political book Tone Inné agus Inniu, where the maestro said: Níor bhain de Valera foréigean as margadh mar fhuascailt, i.e. Dev didn’t rule out violence as a solution.
* Still going strong is ar a sheanléim i gcónaí.
* Take your pick (of them) is bain do rogha astu. Thus, “take your choice from among them”.
* Take your time: for this my old notes suggest tabhair do théarma and tabhair do sheal, but I have this vague feeling that better expressions might exist.
* Wham bam thank you mam is an expression, or an idea, which the old hands of the Gaelic-L e-mail list told me to translate with ní searc go scaoileadh.
* Unfortunately, there is not yet an Irish-language version of Lámhleabhar an Réaltra don tSíobshiúlóir, but I have found a concise idiomatic expression for when men were men, women were women, and small furry creatures from Alpha Centauri were small furry creatures from Alpha Centauri. The little expression is nuair a bhí an saol filiúnta, i.e. when life was poetic. Actually, filiúnta is an Ulster word, and we should probably use fileata in the standard language.
* For wise up! we can use bíodh crothán céille agat or bíodh an trí splaideog céille agat. In the sense “grow up!” you can also use aosaigh suas! or aosaigh ort!