I’ve tried this in a new Dorico document because I thought it might be a problem with imported XMLs but this option (in Engraving Options/Widen gap between [32nd note] beams) doesn’t work. It might seem trivial, but it has an effect on other things, like beam angle.
Dorico will only widen the beam lines if it allows it to choose a beam angle that is closer to the desired slant. This means it will widen the beam lines for 32nd notes if the desired slant is going to be half a space or less, and if at least one of the stem tips at the ends of the beams will end up within the staff. It will not do it if the end of the beam that is within the staff is a longer duration, i.e. if it doesn’t show the full number of beam lines (e.g. an 8th at one end of the beam).
For 64th notes, Dorico always widens the beams, as with four beam lines that’s the only way of ensuring that you get valid sit/straddle/hang positions for all of the beam lines.