Good question! It seems likely that imagery in the other senses is caused by a similar "top-down" control from the prefrontal cortex to the cortical area of the corresponding sense and that electrical stimulation could similarly change the vividness of those types of imagery – but that's just my intuition. (And, as a reminder, we don't know if electrical stimulation would do anything to a sense with no vividness, just that it adjusts the vividness of senses that already have some amount of vividness.)
All good questions! We don't know any of these answers definitively, but seems like something that further research could figure out. I'd certainly sign up for some electrical stimulation to see if I notice even the faintest bits of visualization.