Hello,
from my understanding the KSC library manager works only with Branches, so if you have just several commits to master, then is not possible in the KSC right now and hard to say if it will ever happen.
There are also more issues like Using KSC to migrate mercurial project and libraries to git - Keil Studio / Migrating from Online Compiler - Arm Mbed OS support forum
Few days ago there were similar question and official answer was something like “That is not in the plan right now”. But I also remember somewhere were recommended to use github for the future.
So if some old revisions are essential for you, you have to do it manually.
It is also possible to clone the old repositories to your local disk via TorstoiseHG app. With this, you will also keep the revisions.
BR, Jan