Set a window-configuration-change-hook temporarily, see if the (selected-frame) matches. If so do the split, and remove the hook.

When I hear of a package that may be interesting, I immediately check its repo page to see how many issues and PRs are still open. I look to see whether they have garnered any responses, especially if the submissions are of high quality. Years of issues building up isn’t a good sign. This isn’t 100% reliable, as different skilled developers approach issues and PRs quite differently, but it gives you some information. And there are outliers, like multiple-cursors, whose developer is very skilled and motivated, but whose popularity overwhelmed his resources.

For simple package, “no updates” for 5 years is usually fine. But before investing energy in a larger new package, I want to know whether it will still be working well in the next 5 years.