Tested on Windows 10

modern-configuration
Nightly 77.0a1 -uk build 20200504
region: UA
simulated distribution ini code: yandex-uk

The default search engine for this distribution is Wikipedia(uk) instead of Yandex. Yandex is not present on the search engines list.

The issue here is that we haven't got the relevant file in the build yet, so the configuration for yandex-uk is ignored, and it just picks up another random one as default. I'll get the file added here, though we'll also need a configuration update to get it fully working, I'll incorporate that into bug 1630980.

https://hg.mozilla.org/mozilla-central/rev/e38122dbc38e

Verified as fixed using latest Nightly 78.0a1 20200506093716 under Win 10 64-bit.

Yandex is now the default search engine in the configuration from comment 0, however its icon is "Y" instead of "Я".
The label and the search code are correct.

Should I file this separately or wait until we test the distributions again? Thank you!

(In reply to Petruta Horea [:phorea] from comment #6)

Yandex is now the default search engine in the configuration from comment 0, however it's icon is "Y" instead of "Я".
The label and the search code are correct.

Should I file this separately or wait until we test the distributions again? Thank you!

Thank you for spotting that. I've filed this as bug 1636037 - it is a bug in the search service code, rather than the distribution configuration, though I think this is the only case in which it happens.