Level of risk to tenants for heat pump on a shared type A rcd

"B was recommended more out of panic than reasoned thinking and they had never heard of a Type B RCD before"
That sounds depressingly credible - a lot of designers of the internals of kit are a bit hazy on the rules that apply to the wiring that supplies it - knowledge of the thermodynamics and pumping of cyclo-hexane or whatever the things use  is not a guarantee of  a full understanding of wiring regs and practices in every country where the kit may be installed. And they may well buy in a motor starter/ VFD block and follow the maker's application notes for that rather than design one.
I have had similar " did they not know ?" conversations with suppliers and manufacturers about equipment already on sale that does not actually meet the EMC requirements that it should for the CE mark it sports .. Only usually noticed after there is a very obvious interference problem.

Which is a pity, as fixing problems on the drawing board  at the design stage is far cheaper and more satisfactory all round than a retrospective bodge after installation.

Mike.

Thanks I have this document already, the installer says this information was not available at the time