What means ...
"Bad things are a foot!"
If my memory serves it's when people are trying to do something, like revoke certs and for some reason the cert ID doesn't exist, this error message should never be seen unless people are trying to do bad things to other people certificates. Slightly better then a friend of mines message on another website that really had people wondering "Bad Monkey, Bad Bad Monkey!"
Is there a specific order to follow while translating?
No, you can start at the beginning, in the middle or at the end, but the page Translations/WhatFirst tells you which parts are more important then others.
How to use the translation tools?
Translations tells you how to use the system.
Is there some linguistic help, a glossary?
Yes, of course, have a look at the Translator's Library (english, deutsch, français, italiano, 한국의, Français,日本人, Português, Nederlands, Polski, Español, 傳統的中國, 簡化中國)
Is there some information about CATS translation?
Yes, it is here: Brain/Study/EducationTraining/CATSTranslation