행복 한 교사 하루 = happy teachers day
You can say "സുഖാലി അധ്യാപക ദിനാശംസകൾ" (sukhali adhyapaka dinashamsakal) in Malayalam to wish someone Happy Teachers' Day.
Happy Father's Day in Korean is "아버지의 날 축하합니다" (Abeoji-ui nal chukhahamnida). You can also simply say "아버지, 행복한 날 되세요!" (Abeoji, haengbokan nal doeseyo!), which translates to "Dad, have a happy day!"
Eomeoni-nal or Ŏmŏni-nal
Happy Valentine's Day in Korean is - 해피 발렌타인데이 (he-pi bal-len-ta-in de-i).
You say it in English, just as you would do in the US or any other English speaking country.
In Tamil, you would say "இனிய ஆசிரியர் தின நல்வாழ்த்துக்கள்" (Iniya aciriyar dinna nalvazhthukkal) to wish someone a happy Teacher's Day.
Christian people in Korea say "Ansigil jal boneseyo 안식일 잘 보내세요" to each other
당신 때문에 행복 해요 = because of you I am happy
saengil chukha hamnida
행복 한 결혼 기념일 = happy anniversary
Simply say "Happy Mother's Day."
We {I'm a Korean too :)} don't usually say 'Happy' but there is a word for death aniversary. 기일 Gi-Il I hope that answer is what you wanted!