If one has to believe the numbers that the software comes up with when you save a formation (e.g. 4-4-2, 3-1-2-3-1 etc as auto detected by the program when you save formation) then it would work like this:

for DC, DMC, MC, AMC, ST position has no effect. If you have two or more of them and try placing one much more forward or backward than the other, they are still read as if they were in a row.

for DL/R, ML/R, AML/R, position has some effect, at least in numerical naming of the formation.

Low DL/R are read as in line with DC, High DL/R are read as in line with DMC.
(Very) low ML/R are read as in line with DMC, "normal" ML/R are read as in line with MC, (very) high ML/R are read as in line with AMC
Normal or low AML/R are read as in line with AMC, high AML/R are read as in line with ST.

Note that you can obtain legal formations named 2-6-1-1 (using 2DMC, 2high DR/L and 2 low ML/R) or 2-1-6-1 (using 2 AMC,2 very high ML/R and 2 AML/R)

Whether this really means that a very high (right to the limit of the box) MR will play as AMR, or that a very low MR and a very high DR are the same position for the game, or is just a quirk, I leave as a reflection to the reader