The premise is simple. With a POD between 350 AD and 1000 AD (part of the ethno-linguistic formative years of modern Europe), have Germanic languages be more widespread (by which I mean more majority Germanic-speaking countries).
There are a lot of countries in Europe that were established by Germanic peoples in which they assimilated into the local "Latin" speaking population or were otherwise removed (Franks in France, Lombards in Italy, Visigoths in Spain etc.) and there were, of course other opportunities for Germanic languages to spread.
- Basic level: Northern Italy, Belgium, Northern France, or Poland, Czechia
- Higher level: All of France or Italy, parts of Russia (or any East Slavic countries) or Spain, Finland, the Baltic region
- Advanced: All of Spain, all of Russia, whatever else you can figure out
Consider not only how it comes about, but maybe some interesting effects on History (though this can be hard with such an early POD
This shouldn't be too hard. There's plenty of interesting opportunities.
Disclaimer: I do not think that there should be more Germanic-speaking countries, or support any such expansionism (In other words, I'm not a Nazi, in fact, as my name suggests, I am a Slav). I just made this thread because I think it's an interesting idea to explore.