The way Othello works, playing a legal game requires understanding how the symbols map to the geometry of the board, at least as far as knowing that there are two orthogonal axes on which the tokens are ordered. Playing an "E3" might change the colour of nodes on any neighbouring extent of the 3 rank or the E file. If it's playing a legal game, it's difficult to see an alternative explanation that doesn't map to "it's got an internal representation consistent with an 8x8 Othello board", especially if you directly reach in and make changes to that representation and it subsequently makes moves consistent with those changes.