I took a test on Ranganna a couple months ago that put me at an advanced intermediate level.

First off, as stated, that test is really flawed. Like, it tests your ability to see what's correct in a certain sentence grammar wise (often with rules no native speakers use). It's far from a fair judge of your actual ability in the language, and I'm sure a linguist with a good descriptive grammar and a dictionary could score higher on it without ever learning the language.

Basically, my intent with all this is, if Duolingo works for you, don't be ashamed of it, finish the tree, and if you do that, you'll have more Irish than most of the old country does.

The thing isn't whether Duolingo "works" or doesn't -- the quality of the Irish is poor, and you're not getting the exposure needed to actually learn the language in any meaningful way apart from a few vocabulary words.

because they might not learn any Irish at all if they don't use Duolingo.

If people see this and get put off learning Irish because I don't recommend Duolingo, then they were never that serious about learning it. I gave plenty of resources, and even halfway set out a path to get to a good ability in the language -- without the issues that Duolingo raises. Or, they just want to take the "easy and fun" path of Duolingo, despite the fact that what they're learning (when they learn) isn't really good Irish.