We did similar A/B testing in two industries, financial services and a creative media agency.
In finance, the serious title ('Regulatory Compliance Lead') outperformed quirky alternatives by 3x in qualified applicants. Candidates wanted clarity on scope, responsibilities, and seniority.
In creative media, a little personality helped but only when paired with clear job descriptions. We found 'Creative Producer (Video)' worked better than just 'Video Magician'.
So yes, playful can work but only when the rest of your content backs it up with substance