In the meantime, I tested the urlencode:...|WIKI trick, it runs perfectly for quotes, html tags as <br /> and links wikicode. Now it can be used both for tl|Autore and tl|Intestazione into it.wikisource, and I hope into tl|MediaWiki:Proofreadpage_index_template too. But it fails with templates; templates passed as a parameter are parsed before urlencode can do its masking job. See [[:commons:User:Alex brollo/Sandbox]] for my test, which uses an instance of a modified tl|Book (my interest is focused to Book and Creator templates).
Presently my way for data recovering is a simple AJAX query but as an ecologist I'd like to save both band and server load. :-)
Alex brollo