We're dealing with people who sometimes wear lots of different hats (composer, arranger, perfomer, editor, writer, librettist, translator), so this is the issue that needs resolving. Let's remind ourselves of how this came about...
We started out with page templates for composers only. When recordings came along we introduced templates for performers, some of whom were also composers. So the same person could have two pages that largely duplicated each other, but had different functions. Then we had people who were arrangers, but not composers or performers, so they had to settle for sub-categories within the composer template. The same then ensued for editors, librettists and translators. It's now being suggested that we come up with separate templates for arrangers, editors, librettists and translators, but it's not obvious how these might be used for people who wear more than one hat.
Thanks to Feldmahler's changes yesterday, the composer page now displays works composed, arranged, performed, edited, written and translated by the same person. I'd like to propose that we build on this advance, and have just one "Person page", which covers all the hats worn by an individual. I think it makes sense to have a single portal where all the information on a particular person can be found, with links to the works on the site that concern them.
(Incidentally, I have to agree with PML that the term "Writer" would be better than "Librettist", as it could also be used for authors of musical text books, articles, etc.)
Because the composers make up the largest proportion of the people mentioned on IMSLP, the most expedient approach would be to adapt this for use as a general "person" template. The default references to "composer" can be replaced quite easily by tweaking the composer template, so that it wouldn't be necessary to edit each individual composer page (of which there are nearly 5,000).
One problem area on the composer pages is where we have "Nationality=Austrian composers", for example; however, I gather that Feldmahler has a solution up his sleeve for this one
So we can keep the nationality field without specifying that someone is a composer, editor or arranger, and instead have "Austrian nationals" or "People from Austria", etc. The category walker will allow people to search for Arrangers from Puerto Rico, Writers from Ukraine, or any manner of combinations if they wish.
The person templates can then be extended to all the non-composers on the site, thus removing the large number of red links. We will need volunteers to add the basic biographical details of birth, death and nationality, but that's really small beer compared with many of the projects we've undertaken over the years.
I think this is the next logical step in IMSLP's evolution, and it would remove a lot of the complications of the current system.