Bulgarian and Czech audio is listed as available when purchased from the Bulgarian iTunes Store, using an Apple ID account that is set to Bulgaria. It wouldn’t include both these audio languages for accounts set for other regions.
Downloaded versions may have a subset of the available languages, as configured in TV app settings. Set additional languages that you wish to download, if available in the stream. (This setting doesn’t apply to streaming directly from Apple’s servers.)
If the above doesn’t resolve for your situation, then please contact the iTunes Store staff for issues with purchases of specific iTunes Store titles.