I know this looks like a question that must've already been answered, but I've looked everywhere for a solution.
I'm running ubuntu 17.10 on an 80-key dell Inspiron 11 and I'm trying to add the Latinamerican ("latam") keyboard layout alongside my en (US). The settings GUI lets me add the Spanish ("es") keyboard without a problem, but that has the accent keys in different places. The latam keyboard doesn't show up in the GUI. This wasn't a problem in 16.04.
I've played around with
dpkg-reconfigure keyboard-configuration, but I haven't gotten them to stick. I also plan on adding a few more layouts, but the most important are en and latam.