I had reached out for all of them, but received no feedback of most them, neither via email nor twitter.

Anyhow there are some who contacted me right away to thank me or to ask themselves to be included in PaymentFont.

I see that trademark/copyright thing quite pragmatical. If one accepts a certain payment method or uses a certain payment operator/service, they will anyway put a sticker in their shop window or a logo on their website.

If that happens in good will and context, why should the trademark holder sue you for that? Isn't that actually what they want people to do?