[Plugin: NextGEN Gallery] Search plugin no longer working

I have created a NextGEN search plugin vaguely following these directions:

https://alexrabe.de/2010/01/13/search-for-images/

We upgraded to NextGEN 2.0+ and the search no longer works. I found this thread:

https://www.ads-software.com/support/topic/ngg-20-and-image-search?replies=36

The problem is the nggCreateGallery() function no longer exists in NextGEN 2.0. I followed the direction of the thread and just pasted that function into my plugin. This apparently worked for everyone on the thread. However, my search now throws an error that the class “nggNavigation” does not exist. I found that class from an older NextGEN version and pasted it into my plugin. The search page now returns a string: “We cannot display this gallery”. I found that this error gets returned when the gallery is not “valid”. I have confirmed that the search itself is still working (it is properly finding the two images it should find with the search query), so this is definitely a problem with the nggCreateGalley() function I added in.

Any thoughts?

(the nggCreateGallery and nggNavigation code I added to my plugin is here: https://pastebin.com/HAy2nP7E)