I'd rather leave everything alone if there's anything "non-digit" besides the and splitters in there.
Then leave that part the same as in your original looping regex: 
s[update (\d+(?: and \d+)+) mark complete]{...}ge;

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In reply to Re^3: regex, pos, \G, and substr by ysth
in thread regex, pos, \G, and substr by ff

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