Hi Stephen,
I liked to use the Generico filter in Moodle 3.2 or lower versions but I faced similar difficulties with Generico in Moodle 3.3. Some filter settings seem not to be compatible with Boost or Boost related themes. When you post your experience in Github at moodle_filter_generico, you will receive help from Justin Hunt. He fixed toggle for Moodle 3.3 some time ago.
With kind regards,
Hartmut