"Anna is that child."
Translation:Anna ist dieses Kind.
Given that jenes sounds so formal, would your preferred translation here be Anna ist das Kind?
I don't agree with this translation. With das Kind it's not clear that you mean that child, not the child. You shouldn't use der/die/das as demonstrative pronouns directly in front of the noun they refer to, for exactly this reason. So i would actually say Anna ist dieses Kind. In spoken language you can stress das so that it gets clear that it's meant as a demonstrative pronoun. Look also here. They don't forbid to do it in written language, but it's totally not obvious that you want to point at something. The majority would get you wrong.
It's grammatically correct, just not one of the accepted translations.
Report it if you'd like, though bear in mind that jenes is rather rare in today's German, and using it may make you sound unnatural. (It's a bit like "yonder" in English: technically a word but it has fallen out of use to such an extent that if you use it where the particular markedness is not deliberately intended, you will often sound odd.)