Malheuresement seulement en Anglais
Maybe not answering your question, but touching the subject.
Openworkbench currently stores projects in separate files in rpm or xml format.
Neither can be imported into Clarity.
The standard way is to open each project in OWB and then save the project into Clarity.
In order to be able to do that the resources in the plan must either already exist in Clarity or be created before saving the project.
That is one project at a time. En masse is not possible.
The standard import method into Clarity is XOG and with that you can import projects en masse. Though the same restriction applies as with OWB though it is a little bit relaxed. If the resources does not exist then that data (team membership and assignment is not created, but the project is created).
XOG requires the input to be an xml file. There is a client for XOG which comes with Clarity and you can download it from the UI if you have the permission for that. The Client package has sample xml files for projects to see the structure and data that can be imported.
There are several ways of creating the xml files eg. from data in Excel spreadsheets, but no direct method from OWB views. Copy pasting the data from OWB to Excel and then using, formulas, mailmerge or Excel xml functionality demonstrated by Fedrico Pena of ITRoi to get the xml file(s).
Read the XML Open Gateway (XOG) Development part in documentation.