Fòram na Gàidhlig

m.e.

Rinn mi sin gus an d' fhuair mi seo. = I did that until I got this.
Rinn mi sin gus sin fhaighinn. = I did that in order to get that.

Bha mi a' smaoineachadh, a bheil ciall gu tur eadar-dhealaichte ann eadar an da 'gus' an sin sa Ghàidhlig, no an canadh tu gur e "I did that in order that I got this" a th' ann sa chiad fhear aig an aon àm?

An adhbhar a tha mi a' faighneachd, 's ann a tha mi airson rudeigin leithid "…in order that [x] was/will/would BE [whatever]" ràdh. Tha fios a'm gum b' urrainn dhomh sin a dèanamh le "ach gun" (m.e. "…ach gun robh iad toilichte"), ach an tèid "gus" obrachadh mar sin le "bi" cuideachd?

m.e. Am bi iad seo ag obair? (dearg air rudan mì-chinnteach)

Rinn mi sin gus an robh iad toilichte. = I did that until they were happy / …in order that they were happy. [?]
Rinn mi sin ach gun robh iad toilichte. = I did that in order that they were happy.
Rinn mi sin gus robh iad toilichte. = I did that in order that they were happy. [?]

No a bheil dòighean eile ann?

The red sentence looks weird.

You could also use:

airsons 's gum biodh...
a chum 's gum biodh...
ach am biodh...
feuch am biodh...
ag amas gum biodh...

Tapadh leat, sin na bha mi a' faireachdainn mu dheidhinn nan seantansan dearga.

Ach mar sin — rud eile a bha mi a' faighneachd — am bi, can, "…gus an robh iad toilichte" ag obair mar an dà chuid "…until they were happy" *agus* "…in order that they were happy", no dìreach "…until…"?

Tha gus + cumhadh-ceist a' ciallachadh an dà chuid, until agus so that.

Le so that tha e cumanta an tràth cumhach(conditional) a chleachdadh, mar a rinn Gun Chleoc gu h-àrd.

Rinn mi sin gus an tàinig an dorchadas - I did it until darkness came
Rinn mi sin gus am biodh tu toilichte. I did that so that you would be happy / to make you happy.

Footnote:

My Gaelic-speaking grandparents' generation, and also my (less Gaelic=-speaking) parents, here in the HIghlands, often used until for so that. There can in fact be a certain overlap anyway:

Come over here to the light till I see you better. (Purpose, not time.)
Go over to the fire till you get warm.(With a sense of purpose rather than time, but it will also take time.)

Got it — never occurred to me but we have that idiomatic use of 'till' in Glaswegian too (sure it's common throughout Scotland) so that makes sense.