I think Steinberg’s developers have their hands very full trying to address the major Yosemite compatibility issues which caught them out at the end of last year. I would imagine they want to keep these plug-in products going, since they took a lot of effort to create and are high profile high-end models.
At the moment, the RND Portico and YVC plugins are currently listed as ‘Not officially compatible’ along with several other products.
(https://www.steinberg.net/nc/en/support/knowledgebase_new/show_details/kb_show/steinberg-product-compatibility-info-regarding-mac-os-x-1010-yosemite.html)
Tech support told me this morning that they are working on it, but that their mainstream apps have (understandably) taken priority.