I'm american and remember some high profile movies that featured them. Then again, I'm almost 30. I thought it was common knowledge among many who the IRA were, even among americans.
id say middle age and older people would. they were shown in various movies during the 90s but yea. younger people probably think of the IRA savings account.
I find amusing the "troll" label applied to it. Trolling in my books is someone taking the piss out of someone else or a situation. We're talking about far greater reach here with devastating impacts.
There's certainly some moments that fit this label perfectly, like when Trump announced that he was going to form a joint taskforce with Russia to secure American elections from hackers.
Reusing already-prominent acronyms gets really confusing although I know often it's unintentional.
Many Americans won't know who the IRA were/are, but in the UK (and probably the rest of Europe) it's common knowledge and burnt in.