Is there any special character code I need to enter in JoomSEF config in order to solve this?

Not knowing how your paid support works I have submitted a web support ticket as well, but no response.

Do I have to "buy" support in order to get support on my "bought" plugin?

Is it safe to assume this support forum (and the JoomSEF component development for that matter) has been abandoned from the overall lack of moderation for such a long period of time?

my character site is set for charset=iso-8859-1

assume yours is set for UTF-8

in theory this should solve the problem

My charset has been set to iso-8859-1 as well.

that may be the issue

try setting your character set to UTF-8 as charset=iso-8859-1 is american and UTF-8 is international to support the characters in your alphabet

I don't know 100% if this will fix it, I give it a 75% chance