“according to that note and the linked article”
For context, I was the author of this note (in my pre-account days).

I did a little digging ( http://www.gov.je/pages/search.aspx?query=Maupertuis 😋) which (besides the originally cited URL) yielded the following:
▪︎http://www.gov.je/news/2017/pages/saferoutestoschools.aspx
▪︎http://www.gov.je/government/consultations/pages/proposedstclementsschoolssaferroutes.aspx
▪︎http://www.gov.je/news/2019/pages/ruedemaupertuis.aspx
▪︎http://www.gov.je/government/freedomofinformation/pages/foi.aspx?ReportID=1629# Road Traffic Collisions on Rue de Maupertuis, St Clements (FOI)
▪︎http://www.gov.je/government/freedomofinformation/pages/foi.aspx?ReportID=2862# Closure of Rue de Maupertuis (FOI)

Which give more background & (some) details.

“Maybe a check on the ground to see where exactly the restriction ends / begins.”
Indeed, hence the (earlier) “#SurveyMe”.

Since I seem to be the only surveyor on this island, I guess that'll be me. But, probably in 2022 now.

If Chasse Brunet ( http://www.osm.org/way/167973357 ) is any comparison, then there'll likely be some kind of barrier=yes in the road to physically prevent motor traffic from traversing the length, rather than merely a legal restriction.

From my brief (so far) skimming of the above announcements, there's also some traffic_calming=yes along the way, too.