Macros like the plural form macro only work for logged in users.
How to reproduce:
- Be not logged in
- Navigate to any article, for example https://en.wiktionary.org/w/index.php?title=table&action=edit§ion=4
- Hit "edit"
- Replace {{en-noun}} with some sample plural like this: {{en-noun|xtables}}
- Hit "Show preview"
- Observe that 'xtables' link is red, which means that no macro is attached (for logged in users 'xtables' would be green)