It’s hard to know what to recommend because (just my point of view) no matter how easy the language is, if you’re not ‘into’ the subject it’ll probably be hard to keep your mind tuned in. Of course, it’s worth checking the listings to see if anything on a subject you already like is coming up, and prioritise watching/listening to that.
Although varying dialects in programmes can sometimes throw you, news and current affairs (in any format) are going to be more challenging for learners simply because they use more formal language - there is a lot of “It was reported today that…” kind of stuff said in a way you wouldn’t hear on the street and because you don’t come across it as frequently, it takes ages to recognise and stick in your head (in my experience!).
Perhaps a look through some Welsh clips or songs on YouTube could point you in a direction you don’t mind following, too.
My main piece of advice might be just to have Radio Cymru or S4C (or online stuff like YouTube) on but not go looking for things to understand - just let it wash over you and let the words you recognise find you instead. Eventually (and it kind of sneaks up on you) you’ll realise you are understanding things after all, but it does take patience - far more patience than perfectionism
A couple of final observations - 1. even having played in and worked with Welsh bands for many years, I still don’t understand some of the lyrics!
2. We’re currently filming a second series of ‘Deuawdau’ with Rhys Meirion (and guests!) if anyone’s interested (not one of the things I’m personally involved in though, so can’t tell you much more than that!)