The initial list of possible errors is available on this page https://www.w3.org/International/multilingualweb/lt/drafts/its20/its20.html#lqissue-typevalues
But below is the same list but reorganised a bit according to how the AutoQA's spell check qualities tree in the left panel of task editor
Striked-through lines are irrelevant for the way of how currently spell checking works in Translate5
AutoQA tree name
DB quality category name
Description (to be used as a tooltip shown on quality category mouse over)
The text contains characters that are garbled or incorrect or that are not used in the language in which the content appears.
Content has been duplicated improperly.
The text is inconsistent with itself or is translated inconsistently (NB: not for use with terminology inconsistency).
The text is legally problematic (e.g., it is specific to the wrong legal system).
The issue either has not been categorized or cannot be categorized.
The text is written in the wrong linguistic register of uses slang or other language variants inappropriate to the text.
|Locale specific content|
The localization contains content that does not apply to the locale for which it was prepared.
Text violates norms for the intended locale.
The text contains stylistic errors.
The text fails to match a pattern that defines allowable content (or matches one that defines non-allowable content).
There is a mismatch in whitespace between source and target content or the text violates specific rules related to the use of whitespace.
An incorrect term or a term from the wrong domain was used or terms are used inconsistently.
There is an issue related to the internationalization of content.
The text contains a grammatical error (including errors of syntax and morphology).
The text contains a misspelling.
The text has typographical errors such as omitted/incorrect punctuation, incorrect capitalization, etc.