Agree with Paul. Tagging will be the least of the problems.
The simulation - the really interesting part - is the real issue.
I've been playing with open modelica for the last 5 years or so. Starting and stopping after some months, again and again. The models I handle (Custom made confectionery lines) are so complex and involve so many disciplines, that I cannot really elaborate by myself a working solution. Modelica has - unlike Visio - such a small community, that you cannot get useful (fast) help. Getting a budget for professional help has - this far - been beyond my engagement. So I kept trying and failing by myself again and again.
The solution Vojo suggests would (could) involve modelling the system in Visio, send it to Modelica and get back the results. A connection to Visio - altough it existed in the early days of openmodelica - is badly documented (actually "impossible").
The issue is, Modelica (or better its implementations as openmodelica, simulationX, ...) have their own visualisation tools and therefore would not require Visio.
My (preliminary) conclusion for the subject would be: If someone uses Visio for control loops, then it will always be for a "dumb" visualisation. The intelligence being in a textual explanation.
Intelligent systems will bring their own visualisation.
https://www.openmodelica.org/https://www.simulationx.com/PS: control loops are - unlike fluid systems - already quite good developed in openmodelica. Really worth a look. (Wayne, Paul, ...)