Sorry for my absence in the last few days. I was a little bit busy ...
Thx for your solution with .whdl
Good idea! Works fine. Historyline (DE; EN i don't know!) needs CUSTOM1=2 not =1 ... SORRY. This Parameter isn't documented
=1 means: Play Intro and quit. =2 means skip intro and play. Confused 
Custom Graphics: "Each custom configuration parts of your .uae file will only be used if it starts with the right block name : ;hardware, ;controls or ;graphics" - ahhhhh! Ok:
Works:
;graphics
gfx_width=640
gfx_height=256
Don't work:
gfx_width=640
gfx_height=256
(without ;graphics)
Correct? That would explain why Custom Graphic doesn't work for me:) I will test it next few days ... (busy ...)
"did you manage to test if saves in WHDL are working ok now ?"
NoWriteCache is a good idea because it SHOULD be write immediatly any changes to /tmp/whdl.... Playing with a Save button: works! The score etc. can be found directly in /tmp/whdl... /! Tested successfully in some games.
I saw your Post @ Amiberry in Github about quit an game - Freezes. I'll test something again and then answer back there.
And then i've found a new "Bug" (ok bug is a little bit "hard") ... An improvement in scraping behavior (scraping of Amiga-Games don't work correctly, because screenscraping.fr doesn't recognise Games as Amiga - they recognise it as Megadrive etc.). I will post it in your Github (+ Solution). I think it makes more sense to post that @ Github. Here in the forum you only lose the overview. Should be better used for "how do I get this to run" etc.:). If I should have done it directly there - then we could have spared ourselves the stress communication:) Sorry for that. I will try to make my reports a little bit clearer!