Sudoku grid guaranteed to be solvable?
WLOG the top block is in the canonical order, because we can just relabel, as in 5 -> 1, 6 -> 2, … in your example. I'm not going to make that replacement through the rest of your grid, but will just pretend you started off like that.
+-------+-------+-------+
| 1 2 3 | · · · | · · · |
| 4 5 6 | · · · | · · · |
| 7 8 9 | · · · | · · · |
+-------+-------+-------+
| · · · | 3 2 5 | · · · |
| · · · | 7 9 6 | · · · |
| · · · | 8 1 4 | · · · |
+-------+-------+-------+
| · · · | · · · | 1 5 9 |
| · · · | · · · | 3 2 7 |
| · · · | · · · | 6 4 8 |
+-------+-------+-------+
Making minor-row swaps within one of the three major rows, or making minor-column swaps within one of the three major columns, doesn't change solveability of the sudoku. Therefore we may WLOG that the top-left entry of each of the three grids is 1, by rotating:
+-------+-------+-------+
| 1 2 3 | · · · | · · · |
| 4 5 6 | · · · | · · · |
| 7 8 9 | · · · | · · · |
+-------+-------+-------+
| · · · | 1 4 8 | · · · |
| · · · | 9 6 7 | · · · |
| · · · | 2 5 3 | · · · |
+-------+-------+-------+
| · · · | · · · | 1 5 9 |
| · · · | · · · | 3 2 7 |
| · · · | · · · | 6 4 8 |
+-------+-------+-------+
Similarly we may WLOG that the 5 of the middle block appears in one of two places:
+-------+
| 1 * |
| ! * |
| |
+-------+
because if it's in any of the others, we can row/column swap it into one of those. The exception is if it's in the ! position, which is actually equivalent to the top *. This is because we may transpose the entire grid, and relabel the top-left block again, without affecting the middle block's 1 or 5 except in moving them to the correct positions.
Likewise (but without the option of reflecting this time, because that could mess up the middle block) we may WLOG that the bottom-right block's 5 is in one of three positions:
+-------+
| 1 * |
| * * |
| |
+-------+
There are now $2 \times 7! \times 3 \times 7! = 152409600$ remaining cases, which are left as an exercise to the reader.