The following are good to go:
(?<!abbr>)([Ss])(h<hi rend="[^"]+super+[^"]+">d\.?</hi>\.?)
<choice><abbr>$1$2</abbr><expan>$1hould</expan></choice>
(?<!abbr>)([Ww])(<hi rend="[^"]+super+[^"]+">d\.?</hi>\.?)
<choice><abbr>$1$2</abbr><expan>$1ould</expan></choice>
This is an expression for matching "wh", which as far as I can tell is always expanded to "which", but there are 1128 instances of it in the documents, so we should look at as many instances as possible to conclude that this is always consistent (and that it doesn't sometimes stand for "who", "whom", "what" etc.):
(?<!abbr>)([Ww])(<hi rend="[^"]+super+[^"]+">h\.?</hi>\.?)