It's possible, but there's no "script" to do it yet.
ONLY do this if still have ALL logs from Piwik
1) Update all campaign data in log_visit and log_conversion tables (check out the two columns _name and _keyword). This could be done in SQL using LOWER() function with a UPDATE statement..
2) Delete all archive tables piwik_archive_*
3) Execute archive.php log / script and wait for processing
I haven't tested, but it works by changing the initial raw log data to lowercase and then reprocessing full data
ONLY do this if still have ALL logs from Piwik
1) Update all campaign data in log_visit and log_conversion tables (check out the two columns _name and _keyword). This could be done in SQL using LOWER() function with a UPDATE statement..
2) Delete all archive tables piwik_archive_*
3) Execute archive.php log / script and wait for processing
I haven't tested, but it works by changing the initial raw log data to lowercase and then reprocessing full data