These changes require a Special Bylaw approved by 75% of the owners present at a GM and the bylaw must include a commitment by the owner of the lot to accept responsibility for the changes made to the common property AND accept responsibility for the changes made to your lot to allow for these changes.
If the owners does not submit a suitable bylaw at the next GM I would suggest that you submit a motion requesting that the common areas that were changed be restored to their original condition and set a time frame. This only requires a simple majority in favor to pass. If he fails to do so the Strata can authorize the work themselves and bill the owner the full cost.
If nothing is done once the property is sold the Strata inherit the responsibility for this bodged job and any remediation required.