How to update the Breton flag in the online LT checker?

Hi. When selecting the online Breton grammar checker at https://languagetool.org/ the flag being displayed is the French frag. It’s not ideal. How can we change it to the Breton flag? I.e. this flag: Flag of Brittany - Wikipedia

I already see a Breton flag icon in the LT repo at:

https://github.com/languagetool-org/languagetool/blob/master/languagetool-standalone/src/main/resources/org/languagetool/resource/flags/bytag/br-FR.png

But somehow that icon is not used on the website and I don’t know where the repo of the website is located to attempt to correct it.

The Breton flag is admittedly a bit complex to be rendered at such tiny size.
An alternative flag is the “Kroaz Du” flag (= Black Cross) Kroaz Du - Wikipedia which is simpler, so possibly more suitable for such a small icon. But the available br-FR.png icon may be fine too.