I downloaded and used your layout.  As far as I can tell, it is doing what you asked.  In your layout, the blue dot for the floating text is in the far upper right corner of the template with the rotation set to 180 degrees.  This will place the text upside down just above the top right of the print: because the text rotates 180 degrees around the blue dot.  See attached (first live view on the left).  Even if you add a landscape image that will have to be rotated 90 degrees to fit in the template, the coordinates (and rotation) of the text are translated to the orientation of the image so that the text still appears upside down and above the top right corner of the print (second live view on the right).

Not sure what you were looking for.  You said you want the text to appear at the bottom right short side of the print: but in your layout you have the text (blue dot) at the top right... and rotated 180 degrees.

P.S.  I changed the text color to black and increased the size of the font slightly so we could see the text in my examples.  Those were the ONLY changes I made in order to make things more visible.

Regards,
Mike

Solution:
When you are creating layouts from a "sample" like you are doing, always design them in the intended orientation so the sample image you are working with is not auto-rotated 90 degrees.  So just flip your page to landscape and work that way.  In landscape mode, that landscape image will be in its upright orientation and in that orientation you can rotate the text -90 degrees and place it in the lower right which is what you want.  Then save that as a layout and it will work the way you intend.

Explanation:
The video helps, thanks.  The problem stems from the original photo being auto-rotated.  Templates are just "cells" and they have no orientation with respect to the images that go in them as they have to work with both portrait and landscape images and they won't know in advance which you might put into them.  Images are placed into templates "best fit" which means they will either go into the templates upright or rotated 90 degrees depending on how they fit best.  So when you save as a layout, you have to imagine a red template with no image in it.  And when you look at it as a layout, it is a portrait oriented layout with one template (cell) with text that is upside down and in the top right corner.  The layout can only assume that portrait "cell" is designed for portrait images and you want text to be upside down and in the top right corner of the printed image.

Now when you go to use that layout, remember that the layout only consists of a portrait template that has upside down text in the top right corner of the printed image.  When you load a landscape image into that portrait layout, Qimage auto-rotates the landscape image 90 degrees to the left to fit the shape of the template.  And in doing so, it translates the location of the floating text: notice in your video how it still placed the floating text upside down and in the top right of the photo (when you view the photo upright).  So in other words, it is deducing from your layout that you wanted text upside down and in the top right of the photo so it is doing that even when the photo rotates (so that when you look at the printed photo the text is upside down and above the top right).

Regards,
Mike

I'm not seeing any change in font size with portrait images.  But again, mixing landscape and portrait images (one of which doesn't auto-rotate and the other which does) can create confusion if you intend to place text in the layout.  The templates in a layout don't know whether you will be putting landscape or portrait images in them or whether you meant to position the text relative to the image's orientation or just the shape of the "cell".  So if you plan to do a layout with text specific to placement of the prints, you should probably create one layout for portrait images and another one for landscape images and use them separately.

The other thing that can cause problems is that you have crop turned off so even the shape of the template can change after the image is placed in it (depending on its aspect ratio), creating further "catch 22" issues with point translation and text relative location.  Because you are using image metadata, the text has to be linked to the print otherwise I'd just suggest placing the text on the page and not linking it to a print so the text is linked to the page and doesn't try to "move" with print movements... but you have to (link to the print) in order for the metadata to pick up the image and that link will also link the text location to the location of the image on the page.

Mike