The odd limit is either a number, or a list of numbers like 1.3.5.9.11, which means all ratios involving 1, 3, 5, 9 and 11 or the 11-limit without 7.
The more equal temperaments you consider, the less likely you are to miss something. But this also slows down the search, and if it's too slow the server kills it. The more results you return the slower it gets too.
The figure of demerit is a Python expression in terms of error and width, where error is the optimal RMS error and width is the complexity. You can also use the standard math library, eg math.exp(whatever). The default is width*width*error.
Some gotchas with Python expressions: