I doubt that this feature will actually work in the Librem 5 and if it did work then this would be (very) bad thing.
Yes, it does. And the model that it supersedes (?) says something similar: “Digital Audio and VoLTE (Voice over LTE) (Optional)”.
But this is why Purism would need to be spending the time, effort and dollars in investigating the viability of this module if it is going to make the Librem 5 better overall. (For sure, global support in a single module will be more convenient for Purism, lead to fewer customer questions, and directly benefit a minority (?) of Purism customers. However I would be more interested in more subtle things, like VoLTE support on some networks, and responsiveness of vendor in addressing firmware issues.)
The very first question for Purism (or someone else) is whether the module even physically fits. It should do, based on the published specifications, but there’s nothing like actually verifying that.