Wishing or wish

Hello my friends. I'm wishing a Merry Christmas to my Christian subscribers, and a Happy Kwanzaa to African subscribers. And to all of you without exception, I send friendly thoughts - I hope you and your families are safe and sound during this celebratory period. Happy Holidays!  :-)

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Bonjour mes amis. Je souhaite un joyeux Noël aux abonnés chrétiens, et un joyeux Kwanzaa aux abonnés africains. Et à chacun de vous sans exception, j'envoie mes pensées bien amicales - j'espère que vous et vos familles serez sains et saufs pendant cette période de festivités. Joyeuses fêtes !  :-)


The above is written by an American who is expert in French.

1.I wish you a Merry Christmas.

2.I wish you a Happy Birthday.
I have never learnt to use -ing form when I wish someone.

Before an examination, I am used to saying ' I wish you good luck'. 
Even if you are in the process of writing the examination, I will not use the -ing form.

[ I don't question the French version. To say 'Je vous souhaite un joyeux Noël' is perfect French and I will never translate into English using the -ing form.]
Your thoughts on -ing  form of  the word 'wish' are welcome.

I am wishing is fine. It can mean "I send my wishes" as above, or that at the moment you wish something were other than what it is.

Imagine you are riding in a car on a highway. You find you need to use the toilet. Unfortunately, the last rest stop was 10  miles ago and the next one isn't for another 40 miles. As each mile goes by, you are wishing more and more that you had stopped at the prior one.

As a side note, I don't believe that Kwanzaa is an African holiday at all.  It was invented in the United States for African-Americans.