The loc on the country is working, the party names change. But, the political stuff on the country file doesn't work.

This is the error log:

11:30:02][effect.cpp:391]: Invalid effect 'ruling_party' in history/countries/CZE - Czech Republic.txt line : 22
[11:30:02][persistent.cpp:52]: Error: "Unknown effect-type: ruling_party, near line: 22" in file: "history/countries/CZE - Czech Republic.txt" near line: 22
[11:30:02][effect.cpp:391]: Invalid effect 'last_election' in history/countries/CZE - Czech Republic.txt line : 23
[11:30:02][persistent.cpp:52]: Error: "Unknown effect-type: last_election, near line: 23" in file: "history/countries/CZE - Czech Republic.txt" near line: 23
[11:30:02][effect.cpp:391]: Invalid effect 'election_frequency' in history/countries/CZE - Czech Republic.txt line : 24
[11:30:02][persistent.cpp:52]: Error: "Unknown effect-type: election_frequency, near line: 24" in file: "history/countries/CZE - Czech Republic.txt" near line: 24
[11:30:02][effect.cpp:391]: Invalid effect 'elections_allowed' in history/countries/CZE - Czech Republic.txt line : 25
[11:30:02][persistent.cpp:52]: Error: "Unknown effect-type: elections_allowed, near line: 25" in file: "history/countries/CZE - Czech Republic.txt" near line: 25
[11:30:21][effect.cpp:391]: Invalid effect 'ruling_party' in history/countries/CZE - Czech Republic.txt line : 22
[11:30:21][persistent.cpp:52]: Error: "Unknown effect-type: ruling_party, near line: 22" in file: "history/countries/CZE - Czech Republic.txt" near line: 22
[11:30:21][effect.cpp:391]: Invalid effect 'last_election' in history/countries/CZE - Czech Republic.txt line : 23
[11:30:21][persistent.cpp:52]: Error: "Unknown effect-type: last_election, near line: 23" in file: "history/countries/CZE - Czech Republic.txt" near line: 23
[11:30:21][effect.cpp:391]: Invalid effect 'election_frequency' in history/countries/CZE - Czech Republic.txt line : 24
[11:30:21][persistent.cpp:52]: Error: "Unknown effect-type: election_frequency, near line: 24" in file: "history/countries/CZE - Czech Republic.txt" near line: 24
[11:30:21][effect.cpp:391]: Invalid effect 'elections_allowed' in history/countries/CZE - Czech Republic.txt line : 25
[11:30:21][persistent.cpp:52]: Error: "Unknown effect-type: elections_allowed, near line: 25" in file: "history/countries/CZE - Czech Republic.txt" near line: 25

And this is the country file:
oob = "CZE_1936"
capital = 1
set_research_slots = 3
set_stability = 0.5
set_war_support = 0.5
set_convoys = 0


add_ideas = {
    scraping_the_barrel
    all_adults_serve
    extensive_conscription
    limited_conscription
    volunteer_only
    civilian_economy
}



#For start date 1939.1.1
1939.1.1 = {
    ruling_party = facism
    last_election = "1935.9.18"
    election_frequency = 60
    elections_allowed = no
}

#Politics for 1936.1.1
set_politics = {
    ruling_party = neutrality
    last_election = "1935.9.18"
    election_frequency = 60
    elections_allowed = no
}
set_popularities = {
    democratic = 0
    fascism = 43
    communism = 1
    neutrality = 56
}

#Politics for 1939.1.1
1939.1.1 = {
    set_popularities = {
        democratic = 25
        fascism = 25
        communism = 25
        neutrality = 25
    }
}

#Create country leader - Konrad Heinlan
create_country_leader = {
    name = "Konrad Heinlan"
    #Custom image for Konrad Heinlan
    picture = "konrad_heinlan-86924.dds"
    expire = "1965.1.1"
    ideology = nazism
    traits = {  dictator socialite_connections rearmer }
}

#Create country leader - Otto Von Habsburg
create_country_leader = {
    name = "Otto Von Habsburg"
    #Custom image for Otto Von Habsburg
    picture = "otto_von_habsburg-86909.dds"
    expire = "1965.1.1"
    ideology = despotism
    traits = { collaborator_king unpopular_monarch  }
}

I didnt change any of the text so I don't know what happened.

This is probably due to the name of the country.

When overwriting default nations, you need to use the exact name that the game uses for the files when creating it. So for the tag CZE you need Czechoslovakia - this doesn't affect your names in game, just the files created.

I've swapped the name for Czech. to this, let me know if you're still having issues.

It works now! Thanks