Ah the old as Linux problem of install operating system first and read about it after! I have done this myself. (More than once. 
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This just for perspective: OpenMandriva is a very small all volunteer group much smaller (well less than a tenth) of what Mandriva had. About 4 part time volunteer developers and about that may other active contributors. Unlike Mandriva there are no paid employees. In fact the OMA yearly budget is not enough to pay one full time employee.
In particular we do admit documentation is not as complete as we would like but we are working on this.
This is unfortunate and I still don’t understand why we have not gotten OM Lx 4.1 posted on our mirrors. However we expect new users to first go to what we call our landing page @ openmandriva.org. Right under the “Download” button there is a link to “Release Notes”.
This is the first report of this I have seen. Normally what user sets in Calamares Partitioning step is very faithfully created. If you happen to see this again if you could give more details we can attempt to problem solve whatever is wrong. What to do if user has problems installing OM Lx is discussed here.
Yes there would be dependency issues because the ‘Rock’ repos had been changed from 4.0 to 4.1 so the tool-chain packages are completely different. This was explained here.
So in summary it does seem we have set up something that is confusing to users especially new users. I hope this explains things better about current structure of OpenMandriva. There are more informative articles here.
We do have active discussions after posts like yours about what we realistically can do to make things better.