How can I say
I would be interested to know how it goes.
Would it be
Ich würde interessiert sein zu wissen, wie es läuft.
Not "Ich würde interessiert sein" but "Es würde mich interessieren":
But this sounds rough. This is better:
If you want to use clear German language than there is no "I would ...". It is too subjunctive. It may sound rude for forreigners but: just say what you want instead of saying what you "would want". So say like Hubert wrote:
"Gern" is the only needed polite part of the sentence.
An even less formal version is to ask directly instead to say that you are interested:
(in case you meant something like "does it work?".