I also noticed that picture resolution of similar products are bad. I can’t seem to find a resolution to this problem (not under the picture - quality is 800x800px, not under media (settings). - so I am out of options.
Most likely fonts are not ones to blame but font-width is. They render perfectly fine on Mac even with UTF-8 characters as this theme is built to support that. Most likely Windows or your web browser doesn’t render them correctly.
Try to add this code to Theme Options - Other - Custom CSS
Did you even opened link I provided and read my response there? If you would, there won’t be any questions. Needless to say that screenshot on that forum thread is taken from Unite WooCommerce settings page.
Get rid of css/javascript minification plugin that you have misconfigured or configure it properly. It doesn’t provide any performance in your case when configured that way. It justs creates CSS and JavaScript conflicts.
Maybe this is due to plugin but it appears that you have changed image width to 100% for all WooCommerce images instead of default values.