The relight envelope is where it's been demonstrated a very high likelihood of a successful engine start, as determined by an extensive flight test program (assuming, of course, an otherwise healthy engine). Changes/improvements to the engine after EIS that might affect the restart envelope are few and far between simply because no one wants to do the flight testing needed to re-establish the restart envelope.
Assuming you protect normal engine start limits (principally EGT), the likelihood of engine damage during any in-flight start attempt is minimal.
In other words, if you want to try a restart during drift down to the restart envelope, there is little reason not to.