HA! You just listed every state that used to be part of another state in WWI.
Estonia & Latvia were part of Russia. Lithuania was also Russia. Russia collapsed during WWI, allowing other countries like Lithuania declare independence.
Czechia and Slovakia? Hungary? Part of the Austrian Empire, or, due to civil unrest, was called Austria-Hungary at the time until it collapsed.
Tanzania was definitely part of BOTH world wars. First under Germany, fighting the Great War, then, due to allied victory from that, it fought under the Brits in WWII.
Got me there with Ireland. I'm surprised you didn't say Switzerland.
You can't say that the state didn't fight one war for evidence if the state didn't exist during that war.