Just joined today after having a read of this thread. Have had the SCP9500 since May, although with the Covid situation haven't had much a chance to use it. Although I've not had any major problems with EMI, there is horrid overinking on matte and photo paper. I was so disappointed as it felt like I had a huge door stop. What has helped is profiling papers using the i1Photo Pro 3 with i1Profiler I have and using the PGPP paper setting where PSPP is the suggested media type for the paper as it lays down less ink. This is less than ideal, but it's hopeful.
I was hoping that maybe linearising it would help with the overinking, but apparently that won't help - plus I'd need a RIP for the SpectroProofer I have from the SP9900, because obviously Epson didn't make their Linearization nor Colour Calibration utilities available for this printer.
If there's a dedicated thread on the overinking on the SCP9500 (P9570), please can a mod move this thread. Any advice is welcome on how to overcome this issue without having to throw more money at it - Epson tech support has not been very helpful.
The EPSON EMI program stores under Windows 10 in the directory C:\ProgramData\EPSON\Epson Media Installer\library\SC-P9500 Series\xxxxxxxx\.... the paper settings in form of a XML file for example => P95 EPSON_Prem_Semigloss_Sheet.xml. This file is written when you register a paper via EMI in the printer or when you create your own paper.
I have copied a section for you for a glossy paper.
The InkDensity is 100% for all papers I have examined. I suspect that your high ink application is "not" caused by the media settings. It could be the default profiles or the driver itself.
-<ModeInfo>
<ModeName>2400x1200dpi - 24 Pass Uni SuperPhoto Color</ModeName>
<SurfaceType>0</SurfaceType>
<Pass>24</Pass>
<PrintBiDirection>0</PrintBiDirection>
<ColorNum>10</ColorNum>
<Color>200,201,202,204,210,211,214,215,208,209,205,229</Color>
<White>0</White>
<Metal>0</Metal>
<OnePassLayerNum>1</OnePassLayerNum>
<InkDensity>100</InkDensity>-<Resolution>
<H>2400</H>
<V>1200</V>
</Resolution>
<PMI>10</PMI>
<DefaultMW>0</DefaultMW>
<Intent>4,6</Intent>
<ProfileType>30</ProfileType>
<ICCProfileName>EPSON_SC-P9500_7500_PremiumSemiglossPhotoPaper_CMYK_2400x1200.icc</ICCProfileName>
<ICCProfileNameRGB>EPSON_SC-P9500_7500_PremiumSemiglossPhotoPaper.icc</ICCProfileNameRGB>
<Recommend>0</Recommend>
<InputResolution>300,600,1200</InputResolution>
<DrvLevel>5</DrvLevel>
<DrvBitPerColor>1</DrvBitPerColor>
<DrvMW>1</DrvMW>
<DrvMWSP>1</DrvMWSP>
<DrvHTType>3</DrvHTType>
<DrvOutputType>38</DrvOutputType>
<DrvDefaultIntent>0</DrvDefaultIntent>
<DrvProofingMode>0</DrvProofingMode>
</ModeInfo>
I myself did not have your problem until now. But I also only print unidirectional because of the better precision and the easier head alignment. Furthermore, I have never used an Epson default profile, but always my own profiles. I can provide you with one of my profiles, provided I have a suitable one for your paper.
Regarding linearization:As you can read above, I use a Colorgate RIP. In the creation of a target is always - autarkic - a linearization included. The measurement results from the 5109 Patch Target always contain the measurement results for the linearization (red arrow). You can then derive various profiles of your choice (for example, smoothing, gray balance, error correction, OBAs, etc., etc.) and use them based on the linearization (blue arrow). If your printer drifts from color, you can update the linearization with a few patch fields. The measurement file with the 5109 patch fields incl. linearization will then be mathematically adjusted.

I followed the manufacturer's specifications for the Canson Baryta Prestige 340g with -15% Ink-Density. Red arrow Ink. Density reduced from 100% to 85%. But that would not have been necessary, the paper tolerates 100% without problems in the combination.

I have compared the dot gain from the original Epson Premium Luster 260 profile with my Epson Premium Luster profile.
You can see that the original Epson profile has a larger dot gain (more ink).

However, this does not play a major role in the comparison of the color space size.

I hope the information will help you.
Greetings Gerd