Does your Honda dealership have the L2 chargers for use by Honda owners ?
Would it make that much of a difference in a repair situation? I wouldn't expect the battery to be run down much if any while they are servicing. And even if they did, that's only about $1.00 worth of electricity that I would have to put back into the car so I'm not concerned if the battery is not full when they are done with it.
Has the service dept been trained with all needed infrastructure changes to accommodate the Clarity ?
Not saying that it might not be helpful to have all of that but the fact is Clarity is technically not much different than other Honda hybrids that use i-MMD, other than Clarity also has a charger and some extra cooling etc. So the important thing is only that they have mechanics who can work on hybrid systems.
Is it better if they have training for Clarity? That very much depends, I think training has always been an overemphasized litmus test for whether a competent job will be done. It's not like when you take any car into a dealer that the mechanic has been previously trained on your specific model and even trained on solving the exact problem that you have. In fact car mechanics as part of their daily job work on cars that they have never worked on before, especially when new models come out, or deal with symptoms or a problem they haven't dealt with before even on a popular car. But as long as they have access to information telling them what troubleshooting steps to follow they will usually do fine.
What is most important is that the mechanic is competent, good at troubleshooting, and has a good understanding of car theory, follows instructions, and on top off all of that has experience, good common sense and basic intelligence. That type of mechanic will do a much better job than a less competent mechanic who has had all the training in the world. I learned this from working in a technical environment where I saw just how little impact training has on people if they are not competent to begin with. Meanwhile competent people can excel even without training as long as they are provided the correct information for the task at hand. A dealer mechanic will have access to plenty of information about Clarity as well as the ability to contact Honda technical when needed. So again nothing against training, but people go to shops just because they advertise that their mechanics have received XYZ certification, which often means little more than they sent one of their mechanics to a class and they passed the tests. Much better to check reviews on a shop and try and determine the overall quality of work that they do.