Is this train running on schedule lately? I saw that it was having delays earlier this year.
Which train are you talking about?
The funicular railway does not have a schedule, it runs continuously during opening hours.
No, The Montmartre round trip little train tour. Hop on and off for $9 per person. As seen on Bookings:
Round-trip Little Train Tour of Montmartre
A tour of the Montmartre neighborhood from the comfort of a mini train.
I see reviews from January 2023 on the Paris Tourist Office website. And a review on TripAdvisor from March 2023.
https://en.parisinfo.com/guided-tours/74302/Promotrain-Le-Petit-Train-de-Montmartre
There is a "contact us" section on their website.