Vault version in Foundation is updated for the General Availability (GA) releases. It does not get updated for the Controlled Availability (CA) releases, for example, HotFix releases. 
But, Workbook 2021 SP1 HF2 was a GA release and you see that version in Foundation > Applications.

Also, any time Vault registration occurs in HUB, it will update the version in Foundation. Given below is the info on registering Vault to Hub (manually).

Open an administrator command window on Vault server.
Cd Install_Drive:\Program Files (x86)\BIOVIA\Vault\Utilities

Run the command below using your hub server and vault server name(s)
Symyx.Vault.DatabaseUtility.exe /mode:hubregistration /hubendpoint:https://HUB_Servername:9953 /username:scitegicadmin /password:scitegicadminpwd /vaultendpoint:Vault_servername