I think it is more accurate to say that JBridge integration is built into Cantabile. You still need to purchase and install JBridge if you want to run 32 bit plugins in Cantabile 64.
JBridge allows me to run the VSTs I have which are 32 bit only and unlikely to ever be 64 bit in both Cubase and Cantabile. I don’t have many 32 bit plugins now, just ones where development has ceased so they have no upgrade path. E.g. an excellent Moog Taurus VST which still sounds great , and it is very light in terms of resource demands.
Once you have purchased and installed JBridge, you do not need to JBridge the VSTs for use in Cantabile, it does that automatically once JBridge is installed.
This does lead to a complication as you do need to run JBridge on the plugins for them to run in Cubase (or any other 64 bit only DAW), but not Cantabile. But that is easy to manage. Put the JBridged plugs in a separate directory and point Cubase to look at that one. Point Cantbile to find the original un-JBridged plugins, and both will be happy.
Hope that helps.