How to deal with official country names which aren’t understood by users?

We are using https://github.com/umpirsky/country-list to populate our list of countries in our product. According to some comments I could find (https://github.com/umpirsky/country-list/issues/82), it's basically giving an easily accessible version of the country list database curated and maintained by http://site.icu-project.org/

Unfortunately, some of our users aren't familiar with the correct country names. For instance, one user complained that we don't have England or Great Britain as a country - because those aren't countries and the correct name is United Kingdom. Another user complained that we are missing America - unfortunately there the name is just United States (not United States of America, otherwise they would have found it in our autocomplete box).

While it would be possible to add sort of synonyms to the input fields, like it's suggested in What do you put in a country list for countries with more than one common name?, so that users can find the United Kingdom also as England, I'm very opposed to that idea for 3 reasons:

  1. It's clearly wrong, we'll store the information only as UK and not as England / Scotland / Wales
  2. On other screens we just display the country, so the user would get even more confused. First they choose England, and then if suddenly switched to United Kingdom.
  3. It seems like a lot of work to get it right. Same issue applies for Netherlands and Holland - especially in some German speaking regions those are used as synonyms, and other translations might have, depending on dialects / regions, other confusing synonyms, which we can't know about, unless some user would complain that that language is missing for them.

What is best practice to deal with it, without wasting too many hours on it?

Clearly, educating the users about geography isn't too nice.

Update:

I forgot an important part. The software in question is for the travel industry, and when you have customers / guests you need to register their citizenship / current address where they live. This is the part of the software, where users have trouble with the country list. We use it also in different places, to select the current address of the company or similarly, but there it's fine and there we could improve the usability by checking for IP addresses and similar.

So yes, a person from Netherlands, or even UK probably won't have a problem picking the correct name from the list, but a person from Germany and other countries, which is using the software to register the customer, might internally translate it to England for instance and look for England in their own language.