'Welcome to school' would be学校へようこそ (gakkou e youkoso) in Japanese.
You can say le-le or liyo.https://www.livinglanguage.com/community/discussion/315/saying-youre-welcome-in-japanese-not-recommended
"Irasshaimase." "Youkoso."
You may say 'youkoso.'
Welcome to your School - 'Croeso i dy Ysgol'
シチュー You're welcome.
Welcome to school is gakkō ni yōkoso (学校にようこそ)
When a customer enters, you may say 'irasshaimase.'
'Guamu e youkoso.'
kyoukai e yokoso
学校にいた is how you say I was at school in Japanese.
watashi no heya e youkoso
You wouldn't say "welcome to your school" but "welcome to our school." Karibu shuleni kwetu. Or, to more than one person, karibuni shuleni kwetu.