Go into your connections, data usage, turn on your data saver for a min and then the data saver apps screen and turn everything on off including the system apps since nothing requires that access ever. Then once done go to the apps screen and find the Samsung keyboard app, all of them if there is more then one and make sure to turn on show system apps and see all. If there's more then one and can be hit me back up and we'll fix that. If there's the one then enter its page and do these steps in this order.. scroll all the way down to the btm check version number and tell me and then under app store details which store was it downloaded from?
Go back to the usage screen and change the date week or month and see how much it used then? Go check your downloaded languages and see if more were downloaded and reset the keyboard settings.