Hi Rifton008 ,
you marked a "BAD" for the rendering result with "Printing supplier".
That's rather unusual. Why is that? Did your print job turn out bad?
What kind of printing supplier are we talking about?
The most important question:
Is this really a CMYK + 2 spot-color job?
I inspected your supplied PDF/X-1a with Acrobat Pro DC.
A surprise to me: It does not pass the PDF/X-1a compliance test:

You can fix this with Acrobat's Preflight feature:
PDF/X Compliance > Convert to PDF/X-1a (SWOP)
Button: Analyze and fix
Ok. Let's go on with all other "BAD" results of rendering.
You can do something about that with a different kind of PDF that would not make it through the workflow of a printing supplier and should never be printed on an offset press. For that you would convert all colors to sRGB and simulate overprint.
Compatibilty: Acrobat 4 (PDF 1.3)
Color Conversion: Convert to Target
Target Profile: sRGB IEC61966-2.1
Include target profile
Simulate Overprint
Important: Do NOT convert all Spots to Process with the Ink Manager!
Leave the spot colors as they are before exporting with the settings above.
Screenshot with the PDF viewer of your supplied PDF in Firefox on Windows 10:

Screenshot with the PDF viewer of Firefox after placing the fixed PDF/X-1a to an InDesign document and exported with the settings mentioned above. Note: You cannot avoid stitching artefacts of areas where transparency is flattened!

Regards,
Uwe