I think this does what you want. You might need to add/change the tags in the list_intersection().
Code:
program:
val = $#pagecount;
if $formats && $formats != 'PDF' && list_intersection($tags, 'Graphic Novel, Cookbook', ',') == '' then
switch_if(
val ==# 0, '',
val <# 15, 'Flash Fiction',
val <# 50, 'Short Story',
val <# 100, 'Novelette',
val <# 250, 'Novella',
val <# 500, 'Short Novel',
val <# 750, 'Long Novel',
val <# 1000, 'Tome',
'Toe Breaker')
fi