Works like a charm. BTW, I was gonna say that

m/[A-Z].+?[.;](?<!\.{2,})(?=[^.;][A-Z]|\s*$)/g
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would perhaps be even better, so as to not hardcode any specific number of periods for run-on sentences, but it turns out that:

Variable length lookbehind not implemented in regex m/[A-Z].+?[.;](?<!
+\.{2,})(?=[^.;][A-Z]|\s*$)/
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Sigh. (Oh well, at least there's workarounds; see Why is variable length lookahead implemented while lookbehind is not?.)