"Hot Contacts", as a category name, is really untranslatable. It should
either be renamed, removed, or come with a good and nice translator comment
on what it is really supposed to mean:

#: libedataserver/e-categories.c:234
msgid "Hot Contacts"

This is what rodrigo said on the IRC:

<rodrigo> that is just that, 'hot contacts', people that are cool, good
business relationships, etc
<rodrigo> so, it's like 'important meeting for my business with a new customer'
<rodrigo> that would be an appointment with hot contacts category, I guess