Welcome to OSM o0elMira0o.

I'm glad to see someone citing local knowledge fill in the track.  I was not comfortable doing it from imagery alone having not seen it.

I've changed the tagging from narrow_gauge to miniature and marked the track gauge=184 (mm) based internet sources saying its 1/8 scale.  Do correct that if you have more precise information, as it appears 190 is also an option, such as here.

https://www.openstreetmap.org/way/613631580