I was a bit bothered that using the SQL code as provided in the extension, it created an ascii table. Also it used a different database format from the one mediawiki is using for most other tables.
To align with the utf8 format of all the other databases of my installation, I used the following formula (you'll need to change coetus_coetus.csmw_ in whatever is the right prefix for your database).
CREATE TABLE coetus_coetus.csmw_pagevariable_data ( pgv_entity VARCHAR(255) NOT NULL, pgv_attribute VARCHAR(255) NOT NULL, pgv_value TEXT ) ENGINE=InnoDB DEFAULT CHARSET=utf8;