Did anyone face consequences (charges / court-martial) for the 1914 Christmas truce in WWI?

On the British side, no one was court-martialed. This also appears to be true for the French, Belgians and Germans.

French and Belgian participation in the Christmas truce was, in any case, very limited, and there was no truce on the Eastern Front (as cipricus notes in a comment, Russian Christmas is in January). Turkish troops actually upped their attacks on the (Christian) allies over the Christmas period.

One of the sources cited here (Crocker) has a lengthy bibliography of primary and secondary sources (including two books specifically on the Christmas Truce - Brown & Seaton and Weintraub) and concludes that no punishments were meted out on the British side. If there had been any courts martial, it would be very strange that no one even hints at them, especially after mentioning the orders on the future consequences of fraternization.

In a footnote in a University of Kentucky master's thesis (pdf), T.B. Crocker investigated the British side and states:

The only two cases located, either through the exhaustive research of Brown/Seaton and my own explorations in the Imperial War Museum archives, where a soldier could argue that he had suffered punishment for participating in the truce are of one soldier who claimed he had been denied the DSO because a photograph of him singing in the trenches on Christmas had been published in a British paper, and another soldier who was alleged to have been denied leave after his company commander reported he had been involved in a truce, but neither of these allegations constitute official discipline. No soldier was court-martialed for participation in the truce.

On the French side, the article Fraternisations et trêve de Noël, décembre 1914-janvier 1915, states:

Théoriquement, un soldat français risquait la cour martiale, éventuellement l’exécution (qui ne fut jamais appliquée) pour ces fraternisations.

Translation: Theoretically, a French soldier risked court martial, possibly execution (which was never applied) for these fraternizations.

Another French source, Combler les trous de la memoire (pdf), apparently referring to all the armies on the Western front (French, Belgian, German and British) says there were no courts-martial:

La trêve de Noël ne donna lieu à aucun procès en cour martiale.

Translation: The Christmas truce did not result in any courts-martial.

According to this German source, fraternization between German and French soldiers was extremely limited; soldiers were threatened with court martial but there is no mention of any action being taken.

Another German source points out that the fraternizations were mostly limited to Saxon and Bavarian regiments, and that there was no Christmas truce with the Prussians or the Württemberger.

However, it is probably impossible to be certain as to whether or not any German soldiers were court martialed for the Christmas Truce as the "official figure of 48 executions" for the entire war (1914-18) "is vastly underestimated".

and

Research is... made difficult by the number of records destroyed during the Second World War.

Nonetheless, in commenting on the film Joyeux Noël (2005) on the Christmas truce, Crocker observes that one of the myths that the film promotes is

...that those soldiers who were involved in the event were penalized for their participation...

By this, the author is referring to the (fictionalized) film portraying the French participants as being sent to a "brutal sector of the front", a Scottish troop being disbanded and the Germans as being sent to the Eastern front.

Note: According to Brown and Seaton, cited by Crocker, when Iain Colquhoun was charged with the "approving of a truce with the enemy" during Christmas 1915, it was General Haig who remitted sentence, though how much this was due to the Prime Minister (Asquith, with whom Colquhoun was connected by marriage) is open to debate.

Other sources:

Michael Howard, The First World War (2002)

Hew Strachan, The First World War: Volume 1 (2001)

Keith Robbins, The First World War (1984)