> How would the reader know the writer intended Ge instead of Ga?

Likely because the original paper references Ge, and Germanium has an "r" in it and Gallium does not

I'm with the OP on this one - there is no "Gr" so it's very obviously a typo. Still worse than no typo, but better than if they wrote Ga.

That said, these articles should be issued corrections...

In this case, chemistry of Ga and Ge are a bit different, and the Cr compound that was misstated is part of a family of materials that rely heavily on the coordinating chemistry of Ge and its mates in the same period. So it makes more sense. If indeed it were Ga, that would be an interesting compound that probably wouldn't look anything like the material families being discussed by these authors.

I think the reader and the writer share the burden of accurate communication. The reader should ideally come prepared and the writer should provide as best they can. A prepared reader makes quick work of this typo.