Hi,
I found the solution myself!
It is actually very easy and only takes seconds if you know, where to look. Unfortunately, it took me two days and hundreds of trials and errors to figure out, where to do the tweek. However, you will have to go through this procedure for each plugin, for which you want to change the icon position in the menu, separately. First, you go to the appropriate plugin folder and look out for the action.php or, if present, go inside the "action" subfolder through all existing plugin php files (there are not many and each contains only a few pages of code) until you find the function, commented as:
/** Add button to page tools, new SVG based mechanism */
(This is at least true if you are using the SprintDoc template.) In that function you look for the last line, looking like this:
array_splice($event->data['items'], -1, 0, [new \dokuwiki\plugin<pluginname><functionname>()]);
In this line, the menu item of the plugin (plugin icon) is inserted into the (previously assembled) default array of menu items (which are the default page menu icons, specified in dokuwiki/inc/Menu/PageMenu.php). This procedure they call an "array splice". But how does that work? The splice is applied to the list (array) at one position before the last position (-1). You can change -1 to any other position, e.g. -2, just by overwriting the number. Save the file. Empty the cache (dokuwiki/data/cache). And close/restart your browser. Now the icon of this plugin should have moved up in the row of icons of the Page Tools Menu by one step. If this did not work as expected, because other plugins overwrite the position on the fly and get in between, try out other numbers, to effectively move the icon to the desired position in the array, e.g. -3 or -4 and so on.
Whatsoever, after a few tries it worked out perfectly for me! Now my Page Tools Menu looks nice and tidy!
Yours, Chris
Beware, this change might not be update safe! So keep a note about this tweek in your conf directory and you can make quick adjustments in the future!