Write an alternative engine, and I'll bet someone will make a pragma to switch between them.
Actually afaiui the latter issue is the problem. We already have a framework for "swapping out" the normal regex engine via the use re 'debug'; facility. The problem is that the framework more or less expects the swapped in engine ot behave just the same as the one swapped out. IE, it must set the same globals, and behave in the same quirky way. If this problem could be cleaned up providing an alternative engine would probably be feasable.