Do you ever read and try to understand the material you cite? The "Seafloor Compliance" study is about deformation of the sea floor under pressure from water waves. You have read the terms "gravity wave", "infragravity wave" and "ultragravity wave" and thought this must be how gravity is detected, but nowhere in that study is measuring acceleration due to gravity even mentioned, nor is a measured gravitational acceleration given.
Yes, I did read it. It says that a gravimeter is reading these "gravity waves" which are measured in Hz, therefore a gravimeter is a seismic detecting device. It also shows that seismic data is interpreted as gravity data. The fundamental error here is in not understanding the principled of what is being detected.
Your argument that only some gravimeters are seismometers is spurious. They are all seismometers, and are all measuring the same principle of gravity. We have seen enough information to show that this is the case.
Here is an example of an absolute gravimeters detecting "Gravity Waves". See the caption of the below image:
https://www.researchgate.net/profile/Christian-Ullrich-2/publication/304612229_Poster_Presentation_EGU2016/links/5774c48a08ae4645d60a16c7/Poster-Presentation-EGU2016.pdfMeasurements and Processing:
The absolute gravity measurements in this project were performed with the Austrian absolute gravimeter FG5-242
of BEV and were recorded over two nights and one day at each station; that minimizes errors due to the
determination of the tides correction. Merely at station Saranda the measurements could only be performed during
one night and a half day. Between 4500 and 7000 drops were used at each station for absolute gravity calculation.
Two or three runs (with different laser wavelengths) were performed at each station. The average weighted value of the runs at an absolute gravity stations ( see figure 6,7 and 8 ) is the final absolute gravity value which refers to
exactly 122 cm above the benchmark of each station

In the caption we see reference to detecting gravity waves. The "correlative mean" on 30 September is given as 980270189.75 uGal, but we see in the chart that the actual values presented are very low. The values go above and below 0 over time, just like a seismometer.
A falling object provides an independent reference against the vibrations of the device. It does not make sense that only some kind of gravimeters are basing their fundamentals on the seismic interpretation of gravity, considering that we read that absolute gravimeters detect gravity waves and also produce data which looks like a seismic chart. We will need to see more information from you that an absolute gravimeter operates on a completely different version of gravimetry.