Ok, first answers:
M4x: I corrected that file myself and this time i was finally able to add that fillet, but... on first try it was impossible. Then i remeberred that i enabled refine object on last operation, and quite possibly you created that filet as last operation not just after first sweep like i was trying. And it was first clue - when i tried to do it as last op with refine (i deleted all fillets when correcting model) there was change - malformed face instead of no model at all. Then i found out that if i select edge between ends then fillet is impossible or bad, but if select edge which should be last one the fillet is nearly ok - there were 4mm limit. And at last i selected both end edges and this time fillet was fully ok - 5mm as required and proper faces.
I know about TNP and usually i'm trying to not provoke it but... linking sketch to face is sometimes very handy and natural, also when using fillets/chamfers you need to risk TNP anyway. Especially that sometimes you can't leave them as last ops.
bambuko: well maybe i should try it also...
And now todays parts:
-lubricators for bumpers between loco and tender (there are two in .fcstd, one on picture for better view):
https://para.zonk.pl/Ol49forum/fcstd/02/9.26-01.fcstd
-main connector between loco and tender:
https://para.zonk.pl/Ol49forum/fcstd/02/10.06-0-1.fcstd
-rear mounts for suspension:
https://para.zonk.pl/Ol49forum/fcstd/02/11.14-01.fcstd
-boiler support (there are five in total, three are in previous posts, here is fourth and there will be one more... trickiest one):
https://para.zonk.pl/Ol49forum/fcstd/02/P227-1-0.fcstd
-steps on front bumper:
https://para.zonk.pl/Ol49forum/fcstd/02/P228-1-0.fcstd
-protectors for headlamps:
https://para.zonk.pl/Ol49forum/fcstd/02/P229-1-0.fcstd
-things that protects rails from being greased by 9.26 above
https://para.zonk.pl/Ol49forum/fcstd/02/P230-1-0.fcstd
-and another connector between frames with guides for suspension of first axle:
https://para.zonk.pl/Ol49forum/fcstd/02/P231-1-0.fcstd
and assembly of group 02 with todays part colored - whole documentation is divided into ten groups 00 - 09 where group 02 is for frame, suspension and coupling.