「おもてなし」は「もてなす」という相手を歓迎しサービスを行うという意味の動詞から作られた言葉です。 意味は 通常のサービスだけに止まらず、あなたがとても気持ちよく過ごせるように精一杯努力しますよ。 という自分の気持ちや意思表示を表す精神的な部分を表す言葉の一つです。 Yuki-san ni omotenashi wo youi shimashita this sentence means " I welcome Yuki-san. and I'll do my best for Yuki-san to be pleased."

As you already said, it doesn't have translations and it's really difficult to explain in some words because it isn't only visible hospitality, but also it includes kindness, spirit, respect, etc. Here are some of the articles about おもてなし from the point of view of the peple from overseas. I hope you understand a bit more about it. https://guide.michelin.sg/en/omotenashi https://kbjanderson.com/life-in-japan-omotenashi-the-spirit-of-japans-customer-service-hospitality/ https://www.japantimes.co.jp/life/2015/02/28/environment/omotenashi-japanese-hospitality/#.WlnXe5DXerU By the way, we don't say (someone)におもてなしがよういしました, it doesn't make sense.

The original meaning is to entertain guests wholeheartedly. It's much more than best service and outstanding hospitality. It's thoughtfulness for the guest you are serving right now. Eg: Resturant staff promptly replace the chopsticks when discovering the guest is a left-hander. I'm not sure if this is a good example, but that's how I feel about omotenashi.