Here's the NTSB report
https://app.ntsb.gov/pdfgenerator/Re...Final&IType=FA

An unfortunate event with plenty of opportunities for improvement on all sides.

CAP could have done better in showing their intentions and understanding the traffic situation.
The Barron pilot could have brushed up on landing before instrument stuff.
The Airport could have been clearer on why the spotter was important.

It's a public use airport with random pilots of limited skill and limited visibility. With the benefit of hindsight, there may still be a few possible ways to prevent this.
1) Use a spotter so the glider operation can 'see' 31 traffic.
2) Don't use runway 31 after the intersection. (The defacto plan?)
3) Positive handshake on the radio.
4) Do the glider ops from 31.

2 and 3 don't work with random pilots.
4 would require CAP to be efficient in their use of the runway.
Which leaves 1.