Download only from official Microsoft Volume Licensing channels, match bitness and build versions, and test your XML in a sandbox before full rollout.
To obtain an offline installer for a language pack, you can download the Language Accessory Pack for Office directly from Microsoft. These packs include display languages and proofing tools and are available for both 32-bit and 64-bit architectures. Official Download and Installation Steps office 2019 language pack offline installer
Developers with an MSDN subscription can find the same ISOs under the “Office” section. match bitness and build versions