That depends on what you really mean.
If I say "ya sudah" because I don't care anymore, I'd say "whatever" or "so be it".
But if I meant "i have done it", I'd say "I have".
But if we use Inem's style, then "ya sudah" will become: "yes after"...
How about these 'ya sudah?'
"Kamu kan gak bilang sebelumnya? Ya sudah (kalo begitu)."
"Dia kan gak tau kalo ini bukan salahnya. Ya sudah (jangan diperpanjang)."
"Lu gak bawa duit lagi? Ya sudah (gue aja yang bayar)."
"Gak mau yang ini? Ya sudah (terserah)."
Some Indonesian phrases are quite flexible indeed.