[PROJ] Problems with transformations: projection could not be created and swapped axes with PJ_TYPE_VERTICAL_CRS

[Sebastian Gellrich]

Hello PROJ9 Community,

I have 2 questions about transformations. First of all, I do not know one hundred percent about transformations.
I use a library I built myself for all possible Android platforms.
Now I am testing the library a little and have encountered the following problems:

1.
I get a list of all CRS (PJ_TYPE_CRS) with proj_get_crs_info_list_from_database(...).
For testing purposes, I then create a projection with all CRSs using proj_create_crs_to_crs(...), which I then normalize with
proj_normalize_for_visualization(...).
My source is always WGS84 (EPSG:4326).
With some projections I get the error "No inverse operation" (PROJ_ERR_OTHER_NO_INVERSE_OP) after calling proj_get_crs_info_list_from_database.
What does this mean? Can I somehow create this projection differently?
Example: EPSG:2218

With some CRS of type PJ_TYPE_VERTICAL_CRS I get the error code "Unknown error (code 4096)".
Here the error code tells me even less what the problem is.
Examples:           EPSG:5620
                               EPSG:6357 (here I also received the log message "pipeline: Pipeline: Mismatched units between step 3 and 4" from Proj9)

2.
When transforming to type PJ_TYPE_VERTICAL_CRS, the axes seem to be swapped in the result.
I used the same WGS84 coordinate for all tests (x=14, y=52, z=100 => Germany, Brandenburg).
The transformed coordinates were all x=52 and y=14. Is this intentional?
Some transformed coordinates also contained only Infinity.

Thanks in advance for your help.
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