To test this I generated one with JigsawSudokuExplainer, but can't import it in SudokuExplainer because extra regions are touching.

If 1to9only can manage to import it in his later private version that also supports w-wing, can he check that it solves with w-wing as hardest step?

I solved it by hand but also used the law of leftovers, but suppose that it also can be solved as described before. Can the solvepath confirm this?

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`4.......7.........15......4..3...7..9.1...8.6..8...4..2.......8.........7.......9 112233333111214443211254443222254443615555573688859999688859779688879777666669977`

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`43265...78...14..315..23..4543.6.7.2921475836678...4..2.......83...8....78514.3.9 112233333111214443211254443222254443615555573688859999688859779688879777666669977`

The Jigsaw is solved so far it can be treated as a normal sudoku now

Try to check it now with a Sudokumonster build of SudokuExplainer also not knowing the w-wing technique:

replaced w-wing by larger VWXYZ-wings.

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`Analysis results`

Difficulty rating: 6,4 (VWXYZ-Wing 1310)

This Sudoku can be solved using the following logical methods:

36 x Hidden Single

3 x Pointing

2 x Hidden Pair

1 x Naked Triplet

1 x XY-Wing

1 x WXYZ-Wing 137

1 x VWXYZ-Wing 1310

The most difficult technique (ER): VWXYZ-Wing 1310

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`W-Wing: 2/5 in r2c7,r8c4 connected by 5 in r7c47 => r8c7<>2`