The Swedish translation (and maybe other translations as well) are not included in the latest version (v1.12.2-2.1.3 at the time of writing this), even though it's fully translated. The reason for the uneven percentage (99.7%) is because two strings end with a dot to imply that they are abbreviated, otherwise they would have been going outside their boundaries.

Taken from https://weblate.replaymod.com/languages/:

Taken from replaymod-1.12.2-2.1.3.jar:

This issue was solved at https://www.replaymod.com/forum/thread/2248