The '937 patent covers pibrentasvir, the NS5A-inhibitor constituent of Mavyret that was developed by ABBV itself. Hence, I don't think the '937 patent is relevant to ENTA's royalty steams from Mavyret since ABBV did not license this patent from ENTA.
OTOH, the '807 (glecaprevir) patent I cited in my previous post is eligible for a pediatric extension, which would extend protection by six months to June 2036.