I think you might get more results if you put it in the "family/health" forum, perhaps. I would have seen it sooner there at least - I guess there are other mums who don't check every forum too.
I'm in your catchment area, but if you put together my 20 minutes south of Luzern and someone else's 20 minutes north you're looking at a 40-minute drive each way for those of us who don't actually live in the city. Once an older child is in kindergarten, that can get tricky, as they all come home for lunch and are in school less than 2 hours in the afternoon. People might prefer to have just a couple of central locations to go to. Just a thought, I could be entirely wrong.
I'd be interested if you find enough other interest - or your little one can just come and play with mine one day. She's two and a half. I'm happy to host/be visited any time except Tues, Wed and Fri mornings, from August.
I'm not easy putting the kids' names on a public forum (even though I'm sure the registered members are all lovely!)
By the way there are already some English-speaking playgroups in Luzern too. I am aware of two - one you have to pay for, not sure about the other - could get hold of contact details for you if you like. There's also a cafe with (paid) play area which is run by English-speakers and therefore tends to have expats in with their little ones. Kids under five play while parents have grown-up conversation (or read) - a nice change! Probably you already know it, if not it's called aPlace4us and I expect you can find it on google.
Mika (also 31), in Ennetmoos (Nidwalden)