I don’t recall seeing your profile image, but the “nice” post came off as spammy. Think about it: would anyone actually want to read a post that just says “nice” (or a padded version of that)? Especially in a thread that was dead for several months before that? When you respond to threads, you should do so in a way that contributes to them.
(I should add, contentless posts like that are often created by spambots seeking to edit links into them later, so that might be why it was dealt with harshly.)
Even your post that was allowed to stay up is a little rude and not very useful. You made a good suggestion to include a recording of the problem and it’s cool that you named specific software to look up, but your wording makes the other person sound stupid and makes you sound demanding.
Making a second account to bypass a ban will probably just get you in more trouble. It’s a short ban, just wait it out.
I don’t think a lightly spammy post is worthy of a 7-day ban myself, but it is definitely worth some sort of action here, while it might not be on some other forums. During your ban, why don’t you take a look at some more of the existing threads and replies, and see the sort of atmosphere that’s in this forum? This is a forum primarily for giving and getting feedback and help on all things related to Aseprite, and this of course affects the types of posts that the community deems acceptable.