I don't think combining brackets with parentheses is implemented at the moment. I guess some special treatment would be needed there. Currently parentheses are expanded by including mutliple copies of the move they appear in, with 0, 1, 2, ... copies of the parenthesized group. But if the leading or trailing character of the group would be a question mark in bracket notation, the maximum number of repeats already stands for any smaller number of repeats as well.
So it seems the meaning of parentheses in the bracket notation should be changed, to only indicate the maximum number of repeats. (I.e that indicated as a number behind the parentheses, or a default depending on board size.) The repeat group can then be chained by question marks if less repetitive versions of the move were also desired.
I don't think combining brackets with parentheses is implemented at the moment. I guess some special treatment would be needed there. Currently parentheses are expanded by including mutliple copies of the move they appear in, with 0, 1, 2, ... copies of the parenthesized group. But if the leading or trailing character of the group would be a question mark in bracket notation, the maximum number of repeats already stands for any smaller number of repeats as well.
So it seems the meaning of parentheses in the bracket notation should be changed, to only indicate the maximum number of repeats. (I.e that indicated as a number behind the parentheses, or a default depending on board size.) The repeat group can then be chained by question marks if less repetitive versions of the move were also desired.