Editing Nations (Existing or Extinct)

I'm having some problems with my edited nations with regens.

I have a edited a large amount of nations so different problems are occurring and it's hard to pinpoint what exactly the cause might be.

Errors include:

• Regens spawning with Indian surnames, ethnicity, tamil second language
• Regens spawning with original nation city as place of birth despite city not existing in nation anymore
• Regens spawning born in wrong city (as previous) with the second nation of a related nation to the original edited one (example Netherlands Antilles regens spawning with Dutch nationality and extinct Netherlands Antilles city as place of birth)
• Asian names and ethnicity for regens

I'm wondering what could potentially be a way to rectify these issues

Using an alternative nation to edit, adding more regions to new nation, adding languages to new nation, adding more cities to nation, trying to remove references to edited nation from preexisting agreements, languages, etc

It's hard to know what can be fixed and what can not.

Are there any guidelines on what someone should do when editing a nation to avoid falling into any similar mistakes as these?

Currently I'm working on adding more regions to my new nations as they only have 1 region currently in each respective nation, which may be confusing the AI when designating regens, as well as adding some more languages to try to counteract the influence that the existing nation's data may be having on regens (malay, chinese or tamil for the edited nation's regens)