In terms of that referenced library mentioning “write only”.
A library can choose to use a frame buffer and never read data from the display.
That doesn’t necessarily mean that the module is write only.
For example, the u8glib library operates in “write only” mode
but it still does reads when interfacing to displays like ks0108 and sed1520 to check for ready status.
openGLCD has a read cache mode where it will never read data from the display,
however, it will still read the status from the display to be able to tell when
it can send data & commands to the display.
Are you saying that traces just to the left of each of the labeled fat
ground pin 78 traces are the E signals and go to glcd module pins 6 an 7?
Can you show a photo of the other side of the board?
On the other side are there no traces running to glcd module pins 11 and 18?
If so, there doesn’t seem to be enough pins.
With motorola mode (68 series) you need a r/w pin and a strobe.
With intel mode (80 series) you need a read strobe and a write strobe.
Motorola mode could work if the r/w pin was grounded but then
you could never read the status register to know when commands
There would be no way to run Intel mode since the write stobe pin
is stuck grounded.
It seems very odd that the module would leave two pins (11 & 18) not connected
to anything and hard wire the r/w(WR) pin to ground.
If the module has the r/w(WR) pin hardwired to ground,
openGLCD will not work with the module “as is” since the library
wants to read the status register to know when the module is ready
to receive data/commands.
Without this, the code would have to be changed to use blind delays instead
which requires code changes.
Also, I have no idea how long those delays need to be.