I would start with this Micro Focus page:
Keep in mind that TM ART 4.2 is based on a somewhat aged version of Micro Focus Silk Performer so may need a correspondingly aged version of Rumba.
The real problem is getting Microfocus to allow an older version and that the older version is licensable with their current license mechanism. I am awaiting my national sales rep and a Microfocus tech to come up with a way to deliver an older version.
Does anybody know what BMC Workbench blessed version of Rumba 8 are ( Example: 8.nn)
I don't have access at the moment but the supported release of Rumba and other third party tools should be available in the Release Notes.
There are at least two different release notes documents, one is a rebranded copy of the appropriate Silk Performer release notes. That is the one you want. The other covers TM ART Central and the various BMC-developed integrations.
To finish this story I was able to open an incident with Microfocus ( you have to have purchased support along with the product you ordered). The incident requires a product key with support.
I was able to request a back leveled version of Rumba for 5250 8.1 and now we are in business.
Note: The above mentioned document only states Rumba 8, it does not specify which sub version exactly.
So I am running Rumba 8.1 licensed.