[Doitsu]

Originally Posted by annoporci

Any workaround? I'm on MacOS, is the ebook somewhere in a hidden directory?

You might want to use KindleGen instead. On macOS the latest version can usually be found in:

/Applications/Kindle Previewer 3.app/Contents/MacOS/lib/kindlegen/fc/bin/kindlegen

Originally Posted by annoporci

Note that every Catalan ebook I throw at KindlePreviewer lists the language as English, so it seems that KindlePreviewer has limited support for languages. Perhaps I need to use KindleGen instead?

AFAIK, Kindle Previewer processes all files with KindleGen. I.e., choosing one or the other won't make a difference.

Originally Posted by annoporci

Now KindlePreviewer lists the language as English in `View > Language`, but gives "ca" under `View > Book Information`. Could this be the problem?

Did you add an <x-metadata>...</x-metadata> section to the dictonary .opf file?

Spoiler:

  <metadata xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:opf="http://www.idpf.org/2007/opf">
    <dc:Title>Catalan-English Dictionary</dc:Title>
    <dc:Language>ca</dc:Language>
    <dc:Subject>Dictionaries</dc:Subject>
    <dc:identifier id="BookId" opf:scheme="UUID">urn:uuid:b35c18a7-b81f-47fb-b2f8-aa22fd27da78</dc:identifier>
  </metadata>
  <x-metadata>
    <output encoding="utf-8"/>
    <DictionaryInLanguage>ca</DictionaryInLanguage>
    <DictionaryOutLanguage>en</DictionaryOutLanguage>
    <!-- ... more custom fields -->
    <!-- ... more custom fields -->
  </x-metadata>

and Catalan language codes to the books that you tested them with?

Spoiler:

<metadata xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:opf="http://www.idpf.org/2007/opf">
  <dc:creator opf:role="aut">[Creator name here]</dc:creator>
  <dc:title>[Title here]</dc:title>
  <dc:language>ca</dc:language>
  <!-- more entries -->

  <!-- more entries -->

</metadata>