Page Title Discrepancy

NOTE: The included link is just an example of what we’re dealing with.

I need to explain what we’ve been doing so far before I get to the actual question.

We’re building a new website and I’m tasked with resolving any SEO issues.

Our exhibition pages consists of the main page, a page that shows the reception photos and a page for each of the artists participating in the event.

When I did the SEO audit, we noticed that the main page for an exhibition and their respective reception photos page and artist pages all have the same title and meta description. I tried editing this, but whatever changes to the page title and meta description I made gets reflected in all the other pages. It turns out that these pages were generated with the Art Galleria plugin and that the reception and artist pages had the same URL as the main exhibition page just with a URL parameter at the end to change what content was displayed. What our web developer did was use PHP to make it look like it had a proper URL.

But now we managed to implement a both a title & meta desc. on these pages as well as their non-English variations which are generated with Translatepress. But when I did a new SEO audit, SEMrush didn’t pick up the new meta data. So for example:
The page title that is seen on the Arabic version of the page is “[ARTIST NAME] – [EVENT NAME] – 2018 1 يناير – 1 يناير 1970 – AR – معرض أغورا

But what SEMrush is picking up is: “[ARTIST NAME] – [EVENT NAME] – 2018 Jan 1 – Jan 1, 1970 – AR – Agora Gallery”

I’ve already checked and there are no multiple page titles in the source code. I’ve also checked the “Translate Page” menu to see if there any issues and I can’t seem to find any.

So my question is: Is there something wrong with the plugin that’s causing these discrepancies?

The page I need help with: [log in to see the link]