Jindrich, as to us UK people, you are dealing with a very lazy bunch, I'm afraid, who are even confused about our own national identity. We have so many names for our country and our nation that we don't even realise the differences ourselves. English doesn't really exist as an identity yet for decades we have thoughtlessly used English when we mean British. Very few people know which of the British Isles belong to the UK. Scotland is often referred to as a country. Wales is a principality and Northern Ireland a province. In general we have little patience with these fine distinctions.
However, there is growing interest in the glass of your country. Gradually glass collectors will learn to distinguish the differences in your name but it will take a while. In the meantime Czechoslovakian in an Ebay title is just too long and leaves room for little else. I do use the whole word in the description if appropriate as do some others. As a buyer I have had reason, many times, to question a seller on what it actually says on their label; Czechoslovakia or Czech Republic. I have seen items with a Czech Republic label described as Art Deco! (I'm not talking about Desna repros of Hoffman & Schlevogt pieces) It's impossible to tell if that is deliberate obfuscation, ignorance or just indifference.
Initially, even I found it confusing as someone who knew already knew something about the Velvet Divorce and the Austro-Hungarian Empire and the Bohemia label. So yes patience please and thank you for all your help and your invaluable perspective as a Czech. We value that greatly.