@Mat in the lorem ipsum tiddler there's no "Hello" and no "There" - that's because you don't get the autocompletion. It's not global, only per tiddler and there only per text field.
It may be possible (with help) to extend that autocomplete function, therefor one would have to look deeper into the codemirror docs https://codemirror.net But as of now, the autocompletion works but only with text that's present in the current's tiddler text field try writing "Lo" in the Lorem ipsum tiddler, then hit Ctrl+Space -- You received this message because you are subscribed to the Google Groups "TiddlyWiki" group. To unsubscribe from this group and stop receiving emails from it, send an email to tiddlywiki+unsubscr...@googlegroups.com. To post to this group, send email to tiddlywiki@googlegroups.com. Visit this group at https://groups.google.com/group/tiddlywiki. To view this discussion on the web visit https://groups.google.com/d/msgid/tiddlywiki/f6517915-a736-4a6b-a980-0af2df896040%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.