You can say "സുഖാലി അധ്യാപക ദിനാശംസകൾ" (sukhali adhyapaka dinashamsakal) in Malayalam to wish someone Happy Teachers' Day.
ADYABAKADINAASHAMSAKAL
To say Happy Sunday to all in Malayalam you say "Happy ahad kepada semua".
행복 한 교사 하루 = happy teachers day
aasiriyar dhina nalvaalthukal
Be happy=Santhoshamayittirik
Pithrdina Ashasmsakal. In malayalam, we will not use the exact meaning for happy. All Good Events are happy events. Instead of Happy we use the malayalam word for wishings, ie ashamsakal. Pithr means Father Dina means Day Ashamsakal means Wishes. Hope it is useful. Ashamsakalode (Best Wishes) Salih
ninakku santhosham aayirikkum
How was your day (English) = ningada divasam engana undayirunnu (Malayalam)
You say it in English, just as you would do in the US or any other English speaking country.
Nan enthra santhosama erukkum
athu enne valare santhoshipikkunu
Sukhayathra!, Rasakaramaayirikkatte! (സുഖയാത്ര!, രസകരമായിരിയ്ക്കട്ടെ!)
Puthuvalsara AashamsakalPuthukkala varsham