Does Heavy Light Decomposition have any advantage over Binary Lifting Technique or using a sparse table? Can we solve some type of problem using HLD which can't be solved using the other mentioned techniques?

Hello People! I am new to ACM ICPC, and I want to participate this year. I know that you have to take part in regionals to qualify for Finals. What are xProvisionals/Nationals? Like this: https://icpc.baylor.edu/regionals/finder/india-chennai-provincial-2017

Do they also have slots for finals? I tried googling but I didn't get any answers.

Codeforces allows us to create mashups, and run it as a contest. I noticed a problem in it. If you solve and get AC on any problem in a mashup contest, it won't be reflected in the problem page in the contest from which it was taken. For example, if you solve Problem A from Round 410 in a mashup, and then go to the Round 410's problem A page, it will be shown as unsolved.

Is this a bug? Or was it intended to be like this? (which doesn't make much sense). Or do I have to wait for a certain amount of time for the change to take place?

If this is a bug, please correct this codeforces! Thanks!