Since we don’t have the original SKP it’s hard to say what is different about the missing parts.
If the SKP is purged and fixed under Model Info > Statistics is the DAE any better when imported into a SKP.
Reading the text of the DAE file I see that any tiny exponent-defined floats are written with ‘,’ [from the EU decimal-separator débâcle] whereas decimal floats are otherwise written with a ‘.’
-5.056382E-08 versus -5,056382E-08
However, editing those to be formed with a ‘.’ makes no difference - there are still missing parts - I suspect that the DAE importer already does a ‘tr’ anyway ?
I also note that a material name contains an umlaut ? 'Lärche3’
I’d not expect that to be an issue, but we have no better ideas so far…
Renaming it has no effect.
All imported materials come in named “N” anyway ???
The ‘1’ uses texture ‘laerche2s.jpg’… so I guess that’s it ?
Exporting as DAE from Blender makes a file that fails to import into a SKP completely !
I took the DAE into an online converter and reexported it as a DAE.
That new DAE imports into a SKP and now has no missing parts.
However the textured materials are made 100% transparent ! [fixable by editing], here it is in MonoChrome - showing the missing parts are back ! …
After applying this in the Ruby Console to make all materials fully opaque:
You get this:
So the DAE is salvageable - even when it has such poorly oriented faces…