Keep in mind if you include items in the view template that appear on selected tiddlers, you can introduce code to edit the current tiddler. Typicaly we would not edit only parts of a tiddler with tiddlywiki script in the text field but edit specific fields on the tiddler. These fields value may then be referenced via the template or in the body such that a change to a field is reflected the output.
There remains three ways (at least) to edit a field, in edit mode, in a temp field/tiddler then one done update the field, or edit the field directly (which may cause issues if only partially edited.
I am working on [Proposal] Updating field handling functionality in TiddlyWiki with a view to providing better ways to edit fields, but ultimately this can be used in view mode via the view template.