Hi s-kyy,
thanks for trying out the theme !
I may be wrong (if you know a theme where it works, I may steal the code), but I think it’s a “feature” of Obsidian, the styling of my theme just emphasizes this behavior :
. if the transclusion is a full doc, then it displays the name of the file as a header
. if the transclusion refers to a section/heading only, then it displays the section name as the header
In both cases, you can access the original link by clicking on the small link icon. (in my theme you get the benefit of having a full link for the title when it’s a doc + icon link on the side).
In the image below, I’ve used the default obsidian theme where I’ve transcluded the same doc named ‘Transclusion tester’, the first time as ![[Transclusion tester]], then as ![[Transclusion tester#1990's]]. it’s also ‘missing’ the name of the original file, it only shows the section heading, but since the styling is identical in both cases, it’s not so jarring (even though, I think it could be handled better from the start) :
For my workflow, the current Obsidian behavior was actually not optimal, as I needed to see the transclusions as seamless chapters or inline text blocks (but with subtle hints at their instantiated nature) :
I mostly use a small ahk script to create snippets of texts (crude block referencing) by copy/pasting from longer docs, and create meta-docs made of transclusions, that look like small chapters with their own headings (so I basically never use ![[transclusion#sections]], only transclusions from smaller files).
In order to make the styling work for this specific use, I may have introduced some side-effects and errors, which I may try to fix them unless they are out of the scope of my personnal workflow but I won’t be able to fix everything (sorry 
), but you are very welcome to strip the theme apart and improve or rebuilt it.
That being said, I think the behavior you describe could be a legit request to the obsidian devs to include a textual link in all transclusions cases. It would require some thinking about styling and disambiguation though.
anyway, sorry for the wall of text and thanks again for trying out the theme. cheers.