The website, using Padding Symbols with a Random Character set works. However, copying that config and using the perl module fails.

$ hsxkpasswd -c test.txt 10
ERROR - invalid config from file ./test.txt:
* Reference to {"case_transform" => "ALTERNATE","num_words" => 2,"pad_to_le...} is not a valid Config because it contains one or more invalid Config Key Names:
* 'random_increment'

$ hsxkpasswd -t ./test.txt 10
Distilling the config down to just valid keys ...
WARNING - Crypt::HSXKPasswd::distil_to_config_keys(): distilling out undefined config key 'random_increment' at /usr/local/bin/hsxkpasswd line 82.

Validing the distilled config ...
** Config OK **

Once I remove that argument, the config works.