I think "sede" in this case just means the geographical location where the proceedings are taking place, i.e. a city or town.
As for "concursal", it could mean either insolvency or bankruptcy proceedings, depending on the country and the type of debtor in question.

Not totally sure, but this may work,

The situation becomes even more dysfunctional when insolvent undertakings intentionally manipulate their corporate seat –thus their bankruptcy seat- in the hope of availing themselves of ‘debtor-friendlier’ insolvency law regimes.

https://repository.ihu.edu.gr/xmlui/bitstream/handle/11544/1...

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Note added at 28 mins (2017-10-04 23:51:21 GMT)
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"In case of insolvency" or "in the bankruptcy declaration procedures" could be additional options, just leaving out "en sede". Literally "at the court", but understood as the Company, declaring bankruptcy or insolvency, and doing the needed legal actions attached to that circumstance.




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Note added at 46 mins (2017-10-05 00:09:43 GMT)
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Looking further into this, while "sede" means the physical "seat" or "headquarters", I tend to think this is just an expression to convey the idea of "court-supervised bankruptcy procedures" and/or the fact of being under that process.

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Note added at 2 hrs (2017-10-05 02:09:50 GMT)
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¡Ah!
This is what it really means "en sede"... legally speaking.

Bankruptcy appeal (procedures)

https://jorgemachicado.blogspot.com/2009/11/apelacion.html

Recurso jerárquico. Se llama así en sede administrativa, ****en sede judicial se llama recurso de apelación. En ambas sede se le conoce también como Alzada.


https://es.oxforddictionaries.com/translate/spanish-english/...

Taken from DRAE
http://dle.rae.es/?id=VXlxWFW

recurso de alzada
1. m. Der. recurso de apelación en lo gubernativo.

http://dle.rae.es/?id=2AdjmSS



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Note added at 2 hrs (2017-10-05 02:20:53 GMT)
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So "en sede concursal", I understand is the "phase" previous to any judicial action. It seems to more like a initial phase, before any Judicial Court takes over and handles anything necessary.

I.e., the phase were creditors will get what they can...

https://ar.linkedin.com/company/michigan-bankruptcy-headquar...
Averigua más sobre trabajar en Michigan Bankruptcy Headquarters. Regístrate en LinkedIn gratis hoy mismo. Averigua a quién conoces en Michigan ...

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Note added at 21 mins (2017-10-04 23:44:22 GMT)
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or maybe: in the bankruptcy court but not sure here

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Note added at 3 hrs (2017-10-05 03:18:37 GMT)
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On reflection, I don't think "sede" shoult be taken literally here. It's more like "proceedings"

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Note added at 3 hrs (2017-10-05 03:19:04 GMT)
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should

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Note added at 4 hrs (2017-10-05 03:44:42 GMT)
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just go with "bankruptcy proceedings"