The Vatican does this with latin too. It became a dead language nonetheless.

English always absorbed lots of words from many different languages. I suspect that this is a better recipe for language vitality than the "National bureau of new words" approach.

The Vatican started doing that millenia after there were no native populations of latin-speakers left.

Latin lives on in Spanish, Portuguese, et al.

And in the same sense, your great-grandmother lives on in you. I'm not sure what you're getting at, especially because the Vatican has had an imperceptible effect on Spanish, Portuguese, et al.

I think you are mixing two unrelated concepts: "language purity" and "language preservation". Places like France (and apparently Iceland) are very concerned with excluding foreign loan words, but not because it makes more people become native speakers of the language. As far as I can tell, it's purely for aesthetic reasons. On the other side of the fence, you have the Germans, who find most attempts at "Germanizing" foreign words laughable.

The example of Gaelic here in Ireland is a poor one. The attempt to preserve the language has been badly handled. It is compulsory for every child to learn Gaelic through first and second level education, and never spoken afterwards (except for one or two areas totaling less than 1% of the population).

Many people end up resenting Gaelic after being forced to learn it for no practical purpose. This is a shame because it is a beautiful language to read and speak.

Finland comes close. Swedish is compulsory here from primary to tertiary education. It is only used in coastal Finland, not at all elsewhere.

Of course there is more practical purpose with Swedish than with Gaelic, but nevertheless it does not affect majority's day to day life. It is equally resented because learning is forced.

This must be common; in Israel they've got somebody or other who comes up with Hebrew words to replace the imported ones, and they even teach them to hapless students like me, who go and use them and get laughed at.

"number-witch"?

They didn't have a word for calculate or compute that could have been made into a noun?

Prestidigitization!