I don't think your Serbian deployment was a failure of nerve, I think it's absolutely necessary. On reading post #15 I was going to post to say that it looks like you've done a pretty good withdrawal in Germany without letting up the pressure on Russia, but my only concern would be the lack of pressure on Serbia - I guess it's inevitable that Orm would get an itchy trigger finger in that area when he's under pressure elsewhere.
Your line in the west looks pretty good - no obvious weaknesses or salients, and although you didn't get Rouen or Paris, it looks like you have a firm hold on Calais.
The difficult decision now I guess is how long to wait before reacting in force to Serbia... There's quite a lot of empty Hungarian territory you can conceded before they threaten any production centers...
What would I do? I think:
In the west I'd dig deep and hold the line, with the exception of Antwerp which needs to receive the attention of your artillery pieces. I might even be tempted to rail a couple units away from this front to Serbia or Russia, depending on how your economy is going.
In the east I'd keep pushing. The Russians may well be trying to muster a counter attack, but I reckon right now Orm can't mobilise troops fast enough. I would probe around Riga, and bring up the Warsaw units whilst trying a larger encircling move around Brest-Litovsk.
In Serbia I'd reinforce the flanks of the enemy advance at Sarjevo and Temeschburg to ensure you don't get outflanked, but otherwise allow the Serbs to advance in the centre if they wish (and even maybe encourage them along with a token defence).
That's a lot of things I realise... I'd really like to see a shot of your management screen...