Hi,
Since CleanMart gets integrated to your Joomla Template, as long as your Joomla Template supports RTL... by changing some critical CSS rules, such as;
.floatleft {
float:left;
}
to
.floatleft {
float:right !important;
}
There is no reason why CleanMart wouldn't support it as well. I am not certain about it, because i have never tested CleanMart with RTL before. But we have many clients from Israel and they have been using our Templates just fine. Personally, i remember i have seen PureMart (not CleanMart) in a RTL website. (which was looking good, the client was asking support for something else, it wasn't a question related to RTL). Considering CleanMart and PureMart works the same way(only the visual design is different). It is safe to say that CleanMart will also support RTL.
I wash i have an example in my hand to show you, like.. "look at this website, it is one of our client and using our template in RTL websites". But we are collecting websites for this purpose and very soon we publish them in the product details page. I am sure this will help a lot to see what can/can't our templates do.
But no worry, in case you have any problem with RTL, you will get the support here.
Regards.