The trouble is that, although it translates, the translation doesn't capture what it means. It translates, so far as I know, into something like "I care about my home", but that's not what it means, because you can't divorce the translation from the feelings that a Welshman associates with the line. My attempt to capture that feeling led to a line in Chat that said "I belong here. I'm at home. I'm proud of my country. It's my home. Here is what I'm all about. See Wales? See me?" -- and it still doesn't capture what the phrase means.
How does "July fourth" translate into British English? What about "Quatorze Juillet"? There isn't an adequate translation, not one that captures how hearing the date makes an American or French person feel. How do you translate "Truff" or "Smoffing" into mundane English? There isn't a German word for "Dickensian", or an English word for "Doppelganger".
Language. What a poor tool it is.