No, there isn’t any skill on this yet. There are some community members interested on this kind of topic (a dictation skill to write documents or in your case, spreadsheets).
I proposed a Writing Skill for LibreOffice, and @DaveKimble is trying to do a simple notepad.
I insist that the coolest feature will be the integration between Mycroft and LibreOffice. There are two libraries to work with: PyUNO (for work with the entire LibreOffice Suite) and PyOO, specially designed for work with spreadsheets.
Unfortunately, my development skills are too basic to create something, let’s hope this idea of integrate Mycroft as a true desktop voice assistant hit some curious talented developer.