Increasing the number of attributes ($NUM_ATTR_BYTES) is not recommended at this time. There is a bug in Glulxe which will crash if you try it. I fixed this bug only a couple of months ago (see thread https://intfiction.org/t/glulx-accelerated-functions-and-num-attr-bytes/6499/1) so most people won’t have a fixed interpreter yet.
I7 should never create this many attributes, anyhow. It’s supposed to switch over to individual (I6) properties when it approaches the limit of 48. Are you creating new attributes in I6 code?