Here are some more ways of assigning tags. Hope you find them better than the ones you mentioned.
Filezo lets you directly assign tags from Windows File Explorer. Go to any folder, select the files/folders you wish to tag, right click on them and choose 'Tag files/folders' from the menu.
Another way is to drag the tag from the Tags pane and drop it over the file/folder you wish to assign to.
The new version, allows you to quickly select from the tags list when you type the letter # inside the 'Assign tags' window. This also speeds up tagging.