An edition can make an old text easier to read by modernising its spelling. That choice may be helpful, but it changes what the printed words can demonstrate about the spelling habits of a historical copy.
The TEI discussion of regularisation distinguishes original and normalised forms and describes ways to retain both. The practical lesson for readers is to identify which form an edition is presenting.
Look in the editorial introduction before collecting examples of unusual spelling. If the edition regularises those forms, their absence from the reading text is not evidence that the manuscript used modern spelling throughout.
For a small comparison, choose one securely located word and consult the supplied transcription or image. Record the source form and the reading form in separate columns, together with the edition’s stated policy. Do not label a difference an error merely because the forms disagree.
Keep spelling modernisation distinct from translation and from correction of a suspected copying mistake. They may appear together in an edition, but they answer different editorial problems and require different descriptions.
When quoting, use the text of the edition you name. If historical spelling is central to your argument, select evidence that actually preserves it. This avoids asking a readable modern presentation to support a claim about details it deliberately normalised, while still recognising the value of that presentation for other kinds of reading.
Visual note: the image illustrates the subject, not a documented event.