Decided to have another try with the plugin, inspite of multiple problems with the previous try (some of which I reported here but never received any comments).
This time when opening the guestbook page, I get the following error message:
Warning: mysql_fetch_array(): supplied argument is not a valid MySQL result resource in /websites/123reg/LinuxPackage22/fl/ut/eo/fluteofshame.com/public_html/wp-content/plugins/gwolle-gb/functions/gwolle_gb_get_entry_count.func.php on line 50
Warning: mysql_num_rows(): supplied argument is not a valid MySQL result resource in /websites/123reg/LinuxPackage22/fl/ut/eo/fluteofshame.com/public_html/wp-content/plugins/gwolle-gb/functions/gwolle_gb_get_entries.func.php on line 96
I guess its just not compatible with the latest WP version. I'm just wondering how come no one has come up with a working guestbook plugin that would work on a bilingual site as well...