Can't use past participle with "haven't" in quotes

In some cases Language Tool does not recognize “haven’t” as an auxiliary verb and suggests to replace a past participle with a past tense.

To reproduce type either of those lines (with quotes):

"Haven't you seen it?"

“Haven't you seen it?”

to the form on the front page, select any English language and press “Check Text”. Language Tool will suggest to replace “seen” with “saw”.

Same in LibreOffice.

Works correctly without quotes or in non-interrogative direct speech.

Thanks for your report. Here is what I’ve found out so far. The rule in question is PRP_PAST_PART, and the sentence gets parsed as follows in LT:

<S> "["/``,O] Haven[Haven/NNP] '['/null] t[not/RB] you[you/PRP,B-NP-singular|E-NP-singular] seen[see/VBN,B-VP] it[it/PRP,B-NP-singular|E-NP-singular] ?[?/null,O] "["/'',</S>,O]

But I’m unsure how to fix it. Should we add ‘haven’ as a form of the verb ‘have’ to the English tagger dictionary, or should we rewrite the PRP_PAST_PART rule to use regular expressions rather than the ‘inflected’ attribute?
Also, I am not sure why the rule doesn’t trigger without the quotes.

This has been fixed now thanks to Yakov and a small change to the disambiguation rule.

Best,
Marcin