Hi,
Just a thought, but since a new install doesn't have this problem.
Your issue is related to a Joomla 3.4.4/3.4.5 issue with the modals.
Depending if you have a github patch or not ; you can have an issue or not with the popup parameters.
In the first time, you can revert the Nicolas' patch.
Then you can override the view "backend | your backend template (isis I guess) | product | form" and replace
echo '<div class="hikashop_multilang_button">' .
$this->popup->display(
$lngName, $lngName,
hikashop_completeLink('product&task=edit_translation&product_id=' . @$this->product->product_id.'&language_id='.$language_id, true),
'hikashop_product_translation_'.$language_id,
760, 480, '', '', 'link'
).
'</div>';
By
echo '<div class="hikashop_multilang_button">' .
$this->popup->display(
$lngName, strip_tags($lngName),
hikashop_completeLink('product&task=edit_translation&product_id=' . @$this->product->product_id.'&language_id='.$language_id, true),
'hikashop_product_translation_'.$language_id,
760, 480, '', '', 'link'
).
'</div>';
So it will remove the HTML content in the popup title and avoid that Joomla bug to skip the popup height and width.
And I'm counting the days before the next HikaShop release so we could finally stop using the Mootools Squeezbox and the Bootstrap modal !
Regards,