It would be nice if variables could be interpolated into the strings for the filters.

Currently, the filter strings are in quotes. Without quotes they could just be a string which contains a regular expression subject to variable interpolation:

def arch = 'bar'
def myregex = '.*\\/foobar-\${arch}\\/'
...
recordIssues filters: [excludeFile(myregex)], tools: [gcc4()]

The backslash in front of ${arch} escapes the $ from the RE. if one wanted it escaped from variable interpolation one would need to add another backslash such as
${arch}

Being able to define a list of excludeFile() s in a single variable would be even more useful though. not sure how that could work though.