"I do not make sandwiches for my husband."
Translation:Nie robię kanapek dla mojego męża.
As the comment right above you explains, it should be the genitive kanapek, because it's the object of a negated verb.
Every modern device has the option of adding an additional keyboard layout.
Also, I'm sorry, but I just got to ask this: You've earned 126647 XP in Polish, which makes you one of the most progressed learners I have ever seen on this course. How come you've never encountered the negation rule before? (I assume you didn't, because you didn't recognise it in immery's explanation).
I guess it depends on what you call 'irregular'. A lot of words that have 'ą' in a closed syllable (like mąż), have 'ę' in an open syllable (like mę-ża).
This is due to a historical loss of yers (very short vowels). This same process was also the reason for kościół (ko-ściół) and kościoła (ko-ścio-ła)
The Nominative here is "kanapki", "kanapy" are sofas ;) And Genitive plural would actually be "kanap", just the root.
Insertion of a vowel is common, which probably happens every time when otherwise you'd have two consonants at the end. See here: https://mowicpopolsku.com/polish-grammar/cases/genitive/#noun-plural-feminine
We don't know what 'last time' means, please specify.
The possessive pronoun must agree in number, gender and case with the noun it is referring to.