Regarding the bug, I have been able to reproduce it and I found a temporary solution, though I need to verify whether it has side effects, but I am almost sure it should not.
Make sure the function __toString() in file administrator/components/com_jresearch/tables/member.php looks like this:
function __toString(){
return "$this->lastname, $this->firstname";
}
Before it had the firstname at the beginning. The issue was that the Bibtex standard expects the lastname before the comma, but if there is no comma, it assumes the last word is the last name, leaving no place for names with Spanish conventions (like mine for example).
I will include a fix for this issue in the new version. I am now fixing some important bugs. We should have a new version within this month. Let me know if this helps.
Best,
Luis