ASCII character above 127 is not defined and is up to individual application or hardware to customize it for their own needs. So on the actual LCD display or the online monitoring or the webpage access the could be representing different symbol.
If you want the virtual LCD on the webpage to display these special character then you will have to modify the program that displays the LCD data in the M.JS file. You may need to write a function to read a string and examine each character one by one and then convert the character to the symbol supported by the character set of the webpage.