Silent short film, 21 min, Edmondo De Amicis
–Year: 1915
–Year in film: 1890s ?
–Country: Italy
–Who in clothing: boy ~10, sailor suit
–Who in clothing 2: hist. clothes, night shirt
–Available on DVD: yes
–I own: no
–Clothing occurrence: low-
–Rating: 3/10
–Rating: ***
–Comment: I think only one boy at school with a sailor collar (2 stripes, also rear view). Also other historical clothes at school (suits/uniforms) and at home including a night shirt.
I first thought this would be Dagli Appennini alle Ande (1916). (I have briefly checked that one, no sailor suits found). Same director (Leopoldo Carlucci) and actor (Ermanno Roveri). IMDb missing both director and author for this movie here.
Very few sailor suit. So rating ~2-3 only.
For several versions of Cuore (rating up to 10) see this post.
I also found the source of Unknown #31. It's not from a Heimatfilm but from a 10 year old photo.