Julia just means that she shared this post into her alien art community - the "community account" is an account belonging to that community. The cross-posting thing is up to you, some people do it, others think it is kinda funky in current implementation (myself included). If you cross-post your own post into a community, it publishes a new post to your blog that is basically just a text link to the post you are cross-posting. On peakd.com that text link will appear as the original post, but to the blockchain or on a different front end it is actually just a text link to the post. IMO it is funky to have multiple posts on your blog that are all the same post, with one of them the original and the copies just a text link. But again, lots of people do it so basically I am just sharing an opinion :)
I personally think that what needs to happen is a way to reblog (resteem rehive?) a post into a community, without making a new post appear on your blog. If you reblog someone else's post, it appears in your feed without making a new post - why can't we do the same to share a post into a community? I don't get it personally.
I agree, a reblog into a community would be fantastic, I'm not sure why they didn't do this, I guess it must be a technical difficulty?
I honestly don't imagine it is a technical difficulty as we already have the ability to do that with reblogging posts into our own feed - why couldn't we reblog into a community feed? It seems more like to me the community feature wasn't very well planned out, nor the repost feature.
Possibly, the peak team is usually pretty on point so I'd be surprised if they didn't try it... we can hope though 😂