The only thing you can do is continue to ask the hotel to change the description. Keep in mind that they also have accounting related to that line item which is how they came up with the code in the first place, so they could get in trouble with auditors in the future, which most front desk clerks probably know nothing about.
I don't agree with what you are doing, because you seem to have to hide it and that in of itself is suspect. It would be a lot easier to just explain the code to the employer and most would be okay with that. I have just written down an explanation of the code for my employer and taken a picture of it to upload to my expense report without any problems. My employer is fully aware of what is being done and is okay with it.