as for my experience, it would be challenging to join any consulting firm without knowledge of local language, as this is key to any communication with clients. An additional problem related to the lack of knowledge of local language is that, in case you would manage to join a firm, you may find challenging to network internally with colleagues and senior consultants. This could create a problem for your career growth until you become fluent in German.
As a consequence, applying in Germany compared to a country where you know the local language, you may have the following problems:
- less chances to receive an offer, as there would be less companies interested in scheduling an interview;
- more difficult internal growth, as, until you become fluent in German, you would not be able to network as a local.
Since some companies allow to move internationally after a while, I think the best strategy to land a consulting offer in Germany in the long term would be to:
- apply for a consulting position in Spain, ideally for a company with a presence in Germany;
- move to Germany once you have become fluent in German after some years.
As you are fluent in English, UK could also be an option for the initial application, although you would be likely to find more competition there.
Hope this helps,