Not possible to build targets after translation

[SolenaLeMoigne]

Turning to you, Lingo wizards. I would like to tap in your experience as I am in what seems a surprising situation.
(The names for the project and various files are made up, just focus on the extensions.)
I have received the first package translated from a Flare project. Unzip projet ok, load it into Lingo ok, load translation memory ok. Then checked a couple of topics to have a quick look at the alignment, looks good.
Went into ..\ProjectTranslated.liprjf\Target and opened up the translated ProjectTranslated.flprj with Flare to make the final tweaks before generating the outputs for delivery. Howerver, a couple of things bother me:
1/ I now have three files for each source file: I have a TOC1.htm, a TOC1.xlf and a TOC1.skl. xlf contains translation information, but skl puzzles me most, it contains only exotic characters. What am I to do of this ?
2/ Would this odd structure -and content- help explain why I don't get any targets to build, but right after (or while) processing the CSS, I get the message "Compiler (Internal Error): The current knot cannot contain other knots."
Any pointers? Any explanation? Any "Been there, and this is how I fixed it"?

[SolenaLeMoigne]

And for the sake of completeness, I must add that none of the translated topics display any target language strings.
All I see is my source content, and the flag indicating the topic is meant to be in the target language.

Could something have gone wrong during the import of the translation? I can see all the translation in the translation memory, and I have completed the alignment, so I now have a clean project, except for the fact I don't know where my translation is gone.

Any ideas what could have gone wrong, and more importantly, how to fix it?

[SolenaLeMoigne]

For the sake of completeness, the main issue there was the chair-keyboard interface, the fallible element, the human, me.
One needs to export the translations from Lingo into a new Flare project. And there is a big menu entry to do just that under File \ Export.

So now you know, and so do I.

Doh.