What means this entry in the log files? Uncompiled message detected! Message:

[shrewd briar]

Uncompiled message detected! Message:

Fn3IdG

That means you use raw catalog or your catalog doesn't have a translation for the message and fallback was used.

ICU features such as interpolation and plurals will not work properly for that message.

Please compile your catalog first.

I have several such messages, what I would need to do to fix it?

[vapid lantern]

These are translation errors, nothing to worry about, they should be fixed in following versions