So it was necessary to update the ValentinaPlugin.xojo_plugin in the /Applications/Xojo .../Plugins/ directory and restart a Xojo.
Usually, it is enough to restart the Xojo after updating the plugin, but in that case, we've encountered a crash during compiled application start. Error in the crash log said:
Assertion failed: (pluginEntryTable.GetEntry( entrypointName, out ), "can't find plugin method VVolume.File(index as integer) As VEmbFile"

, function RuntimeLookupPluginEntrypoint, file Common/plugin.cpp, line 990.
Mentioned class was removed some time ago and doesn't exist in the current version.
Xojo has the plugins cache:
~/Library/Caches/Xojo/.../Precompiled Plugins
After removing that cache (with Xojo restarting) an application seems to work again.