SEF link to plugin is not possible.

[Studio 42]

I added this in router file parse function after

Code Select Expand

if (  $helper->compareKey($segments[0] ,'manufacturer') ) {
...
}

Code Select Expand

if (  $helper->compareKey($segments[0] ,'plugin') ) {
$vars['view'] = 'plugin';
if(!empty($segments[1])){
array_shift($segments);
$vars['task'] =  $segments[0];
}

array_shift($segments);
// OSP 2012-02-29 removed search malforms SEF path and search is performed
if (empty($segments)) {
return $vars;
}

}

Then it's not a problem anymore to use a full SEF link to a plugin, WIthout this, if you need any link using jRoute to a plugin fails and redirect to a (unknow) category.
Note: you need this to prevnt each time Joomla redirect in multilanguage sites.