Sorry for the late reply this question appears to have slipped through the cracks.
If you want to block visitors from specific countries reaching your website I would suggest a security extension such as Akeeba's Admin Tools. You can also as you suggested use your htaccess file and in most web host managers such as Cpanel there are options to block IP ranges that you could also use to stop certain country traffic.
If you only want to stop certain countries from being counted in CoalaWeb Traffic's visitor list there currently isn't a specific option to not count certain countries but you could attempt to add an IP range to the Known IP list. I will also add block certain countries to the feature request list for further investigation.
Hi! I'm Steve the founder and head developer of CoalaWeb design studios. I'm an avid supporter of open source projects and the GPL license.