No. Nothing is online regarding Tongan registrations of any sort to my knowledge.Familysearch may contain something but generally it will have been supplied by family.

However various microfilms of Tongan marriages and Wesleyan baptisms and marriages exist. Whether you can access them depends on where you are.

Tongan Government registrations do not usually include persons of foreign nationality. Foreigners generally registered themselves at their own consulates, if there was one. What nationality were the Lombards?

You could search Papers Past and Trove, as often births overseas were mentioned in NZ and Australian newspapers.