Templates are created independently on each wiki. When translating an article that contains a template across two languages, Content translation tries to find the equivalent template in the target languages and identify the equivalent parameters between these templates to copy the information over. This process is currently based on templateData and it is far from perfect.

T221534 proposes to capture the metadata for mappings template parameters in a central repository. While some advanced users may be able to edit this data (e.g., as JSON) directly, it may be more effective to provide a user interface for the task. In this way, we can attract more users to participate.

This ticket proposes to create a user interface to support this process. Users will be able to participate by (a) searching for a specific template they want to map, or (b) coming from Content translation when a template could not be mapped (i.e., an option will be provided for users to fix the mapping).

The basic idea is to show the template parameters (with their description for context) and surface whether these are mapped or not with another parameter. Selecting a parameter allows to pick the matching one from the target template.
Search filters for users to quickly find a parameter, and status filters to decide whether to show all or the unmapped parameters will be provided to facilitate the process for those templates with a long list of parameters.

Further design iterations will add more details.