I have just created a blank project with drupal-6.15 + english (default translation) + nodeadmin-6.x-1.0-beta2
> no problem, works well with add/edit/delete node

I have just created another one with drupal-6.15 + french translation + nodeadmin-6.x-1.0-beta2
> problem with all submit request on click.

Why ?
Because the inputs values are translated: < input type=\"submit\" name=\"op\" id=\"edit-submit\" value=\" Supprimer \" class=\"form-submit\" \/ >

The fast solution:
add other conditions with your translate on nodeadmin.js for functions addSubmit() and editSubmit()

Dev