Last six edges (LSE) and EOLR

Finishing Roux with M and U: orient, place UL/UR, then the M slice.
After CMLL six edges remain: UF, UB, UL, UR, DF, DB, plus the M-slice centres. They are solved with M and U turns only, in three sub-steps: 4a orients the edges, 4b places UL and UR, 4c solves the M slice.
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    4a, EO (the first line that applies decides): First, if the top centre is not the U or D colour, turn M or M' until it is: the edges are read against the centres, and an M turn moves them. Each of these edges has one sticker in the colour of the top or bottom centre: that is its key sticker. Key sticker on the U or D face: good. Key sticker on the F, B, L or R face: bad. M' U M style moves flip edges in groups; the cases go by the number of bad edges (0, 2, 4, 6).
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    4b: bring UL and UR to the bottom together (both on D) and insert them with an M2, matching the corners.
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    4c: finish the M slice and the last edges with M, M' and U2 turns; for example M' U2 M U2 cycles three edges, and M2 U2 M2 U2 swaps two pairs.
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    EOLR combines 4a and 4b: orient the edges in a way that leaves UL and UR ready to insert. EOLRb also handles the centres' parity. It saves a few moves and a look.
Two top-layer edges flipped (UB and UR): a 4a case.
Checked by the engine: bad edges: U1/B1 U5/R1
M' U M U2 M' U M
4c: M2 U2 M2 U2 from solved, a common last-step case.
Checked by the engine: 0 corners moved, 0 centers moved, 4 edges moved
M2 U2 M2 U2