"Four women hug mother and say congratulations."
Translation:Neljä naista halaa äitiä ja sanoo, että paljon onnea.
Onnea is congratulations no need for paljon and why they have että in here is beyond me
One more vote for "sanoo onnea". If the English sentence had "many congratulations" then sure but even then I'm not sure I understand the need for "että" it would be like saying "and say that many congratulations" it's understandable but it's really bad form (in English anyway)
No, because there is a numeral- four. Check out this Finnish grammar help thread for more detailed explanation https://forum.duolingo.com/comment/40624627?from_email=comment&comment_id=41104237
It has not been translated literally (and not even well). The correct translation would be "neljä naista halaa äitiä ja toivottaa onnea" or "neljä naista halaa äitiä ja onnittelee".
(Literally it could be "sanoo onnittelut", but it doesn't sound very good Finnish.)
It's actually a singular subject. Partitive singular, to be more specific. The partitive plural form would be "naisia" and there are also plural forms for every other grammatical case. Noun phrases that are modified by a singular numeral (numerals also have plural forms) tend to be in partitive singular.