Great website.
Although not my field of expertise I know the World Cup finals are a very popular and already well researched topic. Very interested to know your sources - Are you just using the data readily available on the FIFA website or are you cross checking where you can?
Whilst having a quick look I did notice a name that seemed familiar in the 1934 Brazil v Spain match - Ettore Carmanati, who is listed as a linesman.
There was also an Ettore Carmanati who was an active referee in the 1960's.
A quick bit of googling and I found a different forename for the 1934 linesman - Mario ??
http://calcio-seriea.net/arbitri/1934/1/https://www.fifa.com/worldcup/archive/italy1934/matches/match/1111/#match-infohttps://www.worldfootball.net/referee_summary/mario-carminati/3/2/wm-1934-in-italien/https://it.wikipedia.org/wiki/Ettore_CarminatiNot sure if there is a simple explanation or if you need to look further into this.
I noticed on the FIFA site is that for the 1974 Zaire - Scotland match they use different country codes GER and FRG. The country code of GER wasn't used in 1974 and both officials should be FRG. It may seem a bit nit-picking but I thought I would point this out.
https://www.fifa.com/worldcup/archive/germany1974/matches/match/2176/#match-infoThey also refer to the games in the 1934 series in Milan as being played at the Stadio Giuseppe Meazza, when in fact it wasn't named this until 1980!
UEFA also have an annoying habit of doing this with stadium names. It is good to see that you have the correct name - Stadio San Siro
I wish you well with your project and I will keep an eye out as it progresses.