On master, e.g. https://en.wikipedia.beta.wmflabs.org/wiki/Special:ContentTranslationStats I see this message in the debug console:
This page is using the deprecated ResourceLoader module "es5-shim". Use of the "es5-shim" module is deprecated since MediaWiki 1.29.0
It cannot come from the ContentTranslation extensions. It is unlikely that it comes from ULS either. So I don't know where it comes from. The message does not appear in debug mode. This might be caused by the fact that we override the skin for CX special pages. Need help to figure out the real cause.