Good catch, thanks for noticing.
The website is in 'catalan', see https://en.m.wikipedia.org/wiki/Catalan_language
ISO 639-1 for catalan is ca, so i clearly made a mistake by using 'ct'.
But now i am confused why you used ISO 3166 for lookup. Because 'ca' would map to canada there, which is not what i want.
Examples with website:ca seem to lead to pages in catalan language: https://taginfo.openstreetmap.org/keys/website%3Aca

So i tend to website:ca being the correct key here, but i won't make a change before a second pair of eyes had a look :)
greets