I'm not too sure, all I know is that people have had problems with similar things like not being able to access their plot. I don't think it should clear it though, but still, be cautious.
From what CollinPotato(Minetime Owner) has specified, these plugins/features may not work well with name changing: ScoreboardStatistics on OP PvP Skywars (statistics only; balances will be okay) ChestShop on Skyblock and Survival Lockette on Skyblock AlphaChest (/chest) on all servers that have the command There have been no complaints about plots clearing on the Creative server through name changing that I have heard of. My best guess would be to say that your plot would not clear if you were to change your name, however I would wait for more of an expert, perhaps a Minetime staff member, to verify or refute this information. Source: https://www.minetime.com/threads/name-changes.18999/
You keep your plot, if i lost mine, 30 threads would be made about me raging. Really, 20 pixelart and a giant statue that HARRY_HENDO made. Thank god it doesn't.