I have no idea if there's a "normal" way to do it, but in case you don't find anything better and if you're willing to spend a bit of time tinkering, an option could be writing a kate plugin. I did it only once, so my knowledge is extremely poor, but it should be possible to connect to the "text selected" signal, and everytime some text is selected, you read the text document and search if there's a comma or a period etc and in case select the whole number
This is very nice! If you achieve to make it work please share it!