I don't think there is a proper way to do that. Yalp help says that the numbers to enter in Yalp are just incremental based on the updates published to the store by the application maintainer, so if the version you want is the last one before the current version, you would need to let Yalp display the version number first (it shows the last one by default) and then subtract 1 to it. If you don't know how many versions have been published since your target version, then it gets a little more tricky.

I have not downgraded Here WeGo yet so I cannot help, but I'd be grateful if you report back the Yalp version number you had to get Here WeGo 2.0.11457 or 2.0.11539.