A riddle

Textual critics have an unhealthy relation with the phenomenon ‘error’. They find errors in texts just as easily as other people breathe, and consider it their main task to explain the origin of the errors they spot. Nothing brings greater frustration to them than an error they fail to understand.
Here is a nice one. Just take a look at your Nestle-Aland (27th ed.) at Romans 4:20.

It is rather obvious what happened to the word ἐπαγγελίαν here: there are some ink spatters above the ί, even extending to the word τὴν in the line above.
Such errors (of the press) just happen, and there is nothing much to explain about them. My surprise, however, came with SESB, the Stuttgart Electronic Study Bible. SESB is the only electronic edition of NA²⁷ with the apparatus. One would suppose that the SESB publishers/editors received and used an electronic text of the edition. But what does SESB read here? Believe it or not, it is ἐπαγγελῒαν.
Or take 3 John 14. On the printed page, something went wrong just above the word λαλήσομεν.

Just a loose spot, definitely not an accent or a breathing. Still, in SESB, this becomes λἁλήσομεν. Hence my question: how on earth is this possible?