Elementary, my dear HoneyBadger!  =D  I boiled down the examples to the smallest command that caused the issue for me:  !power --a|[[ [A] 1d1 ]] then I dumped out what was being sent to sendChat():  {
   "titlefont": "Georgia",
   "titlefontvariant": "normal",
   "subtitlefont": "Tahoma",
   "subtitlefontvariant": "normal",
   "bodyfont": "Helvetica",
   "titlefontsize": "18px",
   "subtitlefontsize": "11px",
   "bodyfontsize": "14px",
   "txcolor": "#FFFFFF",
   "bgcolor": "#9900ff",
   "erowtx": "#000000",
   "erowbg": "#B6AB91",
   "orowtx": "#000000",
   "orowbg": "#CEC7B6",
   "corners": 3,
   "border": "1px solid #000000",
   "boxshadow": "",
   "a": "[[[A] 1d1 ]]"
}
 I noticed how the expression had changed, so I tried the expression in the regular chat:  SyntaxError: Expected "(", ".", "[", "abs(", "ceil(", "d", "floor(", "round(", "t", "{", [ |\t], [+|\-] or [0-9] but "A" found. and got the same error, then looked through the code for where you were building expressions with [[, and observed the lack of a space.   I also recalled problems with this initially when nested inline rolls were rolled out, which made the correlation easier. =D