you have set the maxlength of all input fields on the settings page to 128 (allowed classes, allowed inline styles, allowed tags). You can imagine that, for example, classes can have very long names, so 128 is much to less for this purposes.

On the html filter settings, the allowed html tags input field is set to 1024 characters. You should take this as a guideline. Also a comment for the allowed tags, that they, unlike the html filter allowed tags, should not be entered with surrounding <> would be helpful.

Nevertheless a settings page per input format and not only globally would increase usability of this filter! Also the locale to use should be able to set to the node's language (e.g. english quotes are different from german quotes!), with fallback: 1. Site's default language, 2. English