[PeterisP]

Iambic pentameter depends on pronunciation, not spelling, and the changes/reforms/standartization generally affects the spelling only. If you take an archaic representation of some sounds and replace it with the modern representation of those sounds, the verse isn't changed.

In that example, "vnknowne" is pronounced the same as "unknown", despite having an extra "vowel" in the typography.

[dragonwriter]

Spelling (and related things) in poetry (especially contractions) often signals intended pronunciation variations from the standard pronunciation of a word.

A mechanical modernization and standardization would seem to run a significant risk of damaging some of these, though proper manual final review would hopefully catch and revert the problematic cases.

[DoubleCribble]

Pronunciation is based on the spelling.

How many syllables are in the word 'wandring'? How many are in the word 'wandering'?

Sadly, the modernization breaks the meter and it's no longer a sonnet. I have a sneaky suspicion The Bard was deliberate in his choice of spelling...