I had an email from Christian Askeland, who tried (and failed) to comment on the Coptic posts, but kindly emailed me anyway. Spam is such a nuisance; you get rubbish you don’t want, and lose stuff you do. But the email was so useful that I post it here.
1) Your editor is technically incorrect to label Keft as “Sahidic”. Most people would agree with your editor against me on this. The reality, however, is that Sahidic was written in three different scripts: Biblical majuscule, Alexandrian majuscule and Sloping pointed majuscule. The last was generally used in non-literary documents. Because most of our Bohairic manuscripts date from the 11th-19th centuries, most of them appear in a script developed from the Alexandrian majuscule, and this is considered a Bohairic script. The fact is that early Nitrian Bohairic manuscripts appear in biblical majuscules. Even earlier papyrus manuscripts such as the early Bohairic of John and the Minor Prophets use an informal version of the Biblical majuscule.
Having said all this, feel free to use a font which represents your manuscript’s time and style. If I were to restart my project, I might use Alphabetum to distinguish my Medieval Bohairic texts.
The major issue is this: how anal are you with your transcription? Keft is a superior font, having been designed by the IACS for about 10,000 Euro under the auspices of Stephen Emmel. Primarily, Keft excels in being able to handle combining superlinear strokes in Sahidic. Perhaps, this is not an issue in Bohairic.
2) The diagonal lines over Bohairic characters are “djinkim.” The are functionally the same as the dots, although the dots were used in earlier manuscripts. In the late fourteenth century, a more expansive system of these dots developed, allowing a rough kind of dating based on these superlinear marks. There is no translational significance to these marks. Some marked vowels, some were reading aids.
Are you using this keyboard? It is free, and is designed for Microsoft Word.