This is a silly.comment unless you know the application and the domain. Excellent answer on all the things the go into an Internet facing app. Plus Education is a tricky area because the outcomes are complex - what are the paths to a certificate, diploma, certificate. Khan Academy probably wound up writing the original Python code themselves instead of a COTS product.

I'm not a big fan of LOC as a metric. You certainly can't compare languages. But the point that this is a large app and the builders are happy with their product and choice says a lot.

YMMV