As withCU3, the EN download is available by default. All other language packages will be made available on need basis. If a download is not available for the supported BizTalk language that you need, please contact us for the same.
As a quick reminder, for BizTalk Developer Tools please also update/install version 184.108.40.206 of the BizTalk Server Visual Studio extension in addition to installing the CU package. The extension can be installed from https://marketplace.visualstudio.com/items?itemName=ms-biztalk.BizTalk or from within Visual Studio - Manage Extensions. Please note that we have not updated the extension since CU1 so you can skip this step if you have already installed it previously.