Fighting with Eleventy

Over at daily.baty.net, I've been trying to wrangle Eleventy into showing the posts I want on the home page, in the order I want them. I've completely failed so far and it's very frustrating. I don't think this is at all the fault of Eleventy. I'm just really slow to pick up new things.

I have two tag-based "collections" in Eleventy: Journal and Post. I've always only shown "collections.journal" on the home page but I wanted to include regular blog posts, too. Do you think I can figure out how to do that? Nope. The closest I've come is to create a custom collection like so:

eleventyConfig.addCollection("myHomeCollection", function(collectionApi) {
        const journals = collectionApi.getFilteredByTags("journal");
        const posts = collectionApi.getFilteredByTags("post");
        return allHomePosts = [...journals,...posts];
    });

This gets me the correct set of posts, but they're sorted first by tag and then by date, so it's unusable on the home page. I want reverse-chronological over the entire array but I've no idea how to do that. I'm so dense.

In the template, I use the reverse filter, { % for post in postslist | reverse % }, but no joy. What the heck am I doing wrong here?