Today I spoke to the Nicaraguan Embassy in Austria. There is no possibility to apply for a long term Visa for Nicaragua in Austria. They say you have to enter the country and proceed the process on site.
Anyways, I will tell you all you need to know about extending your tourist visa in Nicaragua.
OPTION 1 – MIGRATION OFFICE
OPTION 2 – LEAVE THE COUNTRY AND REENTER
OPTION 3 – OVERSTAY