I did indeed-- there are some Irish-language segments in A&D so I like to do my holiday messages in Irish, and Samhain seems to be a well-known enough bit of Irish/Scots gaelic that everyone recognises it!
edit: I typed that and then realised the word "Samhain" doesn't actually appear in the message. Oops. "Shámhna" is a derivative of Samhain; "How-nah" as opposed to "Sow-an". It makes more sense in Irish!!!!!
I am impressed. I always wanted to learn the Irish/Scottish Gaelic (my actual name is Aisling/Aislinn, but Mom spelled it Ashleen because she rightfully had little faith us in the US could pronounce it. I never get called my actual name unless I say it, and even then it's iffy).
To be fair, I've seen non Irish speakers trying to read Aisling and it's not pretty, so your mom may have been correct. Duolingo has a pretty good Irish course! I've been using it to practice :b
"Oíche Shamnha shona duit" -- Happy Halloween [Night] To You
"Le gach deá ghui" -- With every nice wish, best wishes; a sign-off for a letter or message
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