I haven't read Mallory in many years, so I don't remember. The last Middle English I read (other than recipes and song lyrics) was from the Canterbury Tales, in a student's edition that had same-page footnotes translating most of the unfamiliar words, rather more of them than I needed. Tolkien's edition has endnotes discussing where there's a gap or missing ink in the ms, and the concomitant possible alternative readings, and what the use of this word rather than that says about the author's geographic origin, but doesn't lower itself to "this Middle English word means that modern English word."