(ie without capitalizing the N in newsletter and using quotes), here’s how my channel is coded (don’t forget the indents too)
/latest-core/:
controller: channel
template: latestcore
filter: ‘tag:-hash-noncore’
sorry, can’t help you then, I’m a noob too…if you are trying to create a channel with a single tag, then you would have a tag page with the same list of posts (ie as per your taxonomies)…best I can do!