Help in Spanish Wikisource
This feature was missing in the JavascriptScript we use for modernization, although it was already available in the LanguageConverter from MediaWiki, which is a tool I've suggested on multilingual wikisource (before knowing of the French modernization script):
I've made a change in the script which seems to make it possible to isolate parts of a page which shouldn't be converted. You can put a class in an HTML element, as in <span class="no-convert">i</span>, to avoid the conversion of the text inside that element. The name of the class can be configured using the parameter "no_conversion_class" added in this edit. It worked in this test.
About the other problem, you can try to use the rule "páj: pág", without the dot (which can't be put in the alphabet, since it would make thinks more difficult).
Just a note: It seems that the MediaWiki caches the API call used by the script, so after adding new rules to dictionary, it takes some time before they start to be used (I don't know how long does it takes, neither how to purge that cache, unfortunatelly...).
PS: I'm sorry for that typo.