Ah, thanks for clarifying @theSocialIntrovert, that's clearer now. I think you meant something like flashcards rather than the cards I had in mind when answering.
@riffy36 Too bad, but we don't know you and don't have anything against you or your suggestions personally, and you were never told to stop posting.
When something is suggested, it's very easy to say do this or do that, but the point of a forum is also to try to constructively explain why your suggestion is useful, which benefits it could bring and why it should be added.
Even then it might be accepted or refused, the Playroom is a free, hobbie project, so there is really no obligation to do anything. That's not anything against your suggestions or against you, you should just be ready to accept and hear out the other side and try to answer the questions, that's the whole point of a forum.
Maybe five of your suggestions will be refused and one will be accepted, or maybe it will go the other way round, it depends on a lot of factors, from the time it will take to implement it, the usefulness of the suggested feature, the motivation of the developer to work on that particular part of the Playroom at the moment (even if something is refused today, it does not mean it will never ever appear).
Nowadays I've been hearing a lot of these complaints of X thing got refused, so Y thing that I am suggesting will probably never be added and will be refused too, which is simply not true. Don't connect entirely unrelated suggestions, be respectful and polite, and you have as much chance of your suggestion being accepted as everybody else.
When developing, there are many factors you have to consider. For instance, with your feature, you have mentioned that the users should be able to play their own custom sounds. Now, here we have one interesting challenge: These sounds have to be stored somewhere on the server so that the users can download and play them. What happens if you upload a bunch of copyrighted sounds that you illegally obtained? Of course, you clearly broke the rules in that case, so it's your problem, except that the complaint goes to the Playroom team and it has potentially dangerous legal consequences.
Obviously, I am not saying you will do that yourself, I'm just saying that this opens up a potentially big loophole for legal issues. That's in fact a bbig reason why you propose a link to an audio stream instead of just directly streaming and uploading files for all other users, then the responsibility is on you/the website hosting that stream.
In summary, as long as everybody stays constructive and explanations are clear/you are ready to clarify any misunderstandings, you can suggest whatever you want, just take it for what it is, a suggestion, not a demand or obligation.