Elena, both “Is your proposal still in force?” and “Is your proposal still valid?” are not quite idiomatic. The common question is “Does your offer still stand?”.

+++Olga

Thank you, Uly. I deleted these translations.

They were just a little too contractual)

But are they used in business? I was pretty sure they were...

Yes, mostly in contracts and business correspondence.

Ok, thanks! Uly, can you have a look here: https://www.lingvolive.com/en-us/profile/fcd47b32-fe23-4f09-8db7-8d071c51b110/questions

Done!

Great! Thank you⛄

👍🏼