This is not a bug but a suggestion.
I've got several of these fields in my tree. The input of one of them (a Pict Name) is:

{?EN:Tremblay's 'Dîmes' Barn}{?FR:La grange aux dîmes de Tremblay}

I lately tried to generate an ES (spanish) Report and I got this:

As

you can see, there's no title. This is because the equivalent {?ES:...} input doesn't exist.

My suggestion, therefore, is, in order to get the title of the Pict, to sustitute my missing entry by the 1st input. In my case it will be the {?EN:...} text.
Alternatively, a substitute default language parameter could be set in config.xml.
I would personally be happy with the 1st solution.
Thank you,
JC