Are the Newsletter archives searchable in any fashion?
Unfortunately, no. A manual search is required.
At the very least, the text
is searchable once the file is opened. So you can use Ctrl+F to find things, you don't have to read every word. A few years back I led an effort to add searchable text to the older scanned issues that lacked it. The embedded, computer-generated text in those scans is not 100% accurate but it should be "close enough" to find subjects of interest.