Server Valhalla is nearly a decade old, it has been around since 2012.
One of the things that sets this server apart is its longevity, and no map resets. The map since the first anvil format (Minecraft 1.2.1) is still around. One of the promises kept back then is no map resets, and that is still being honored. The old map from nearly a decade ago is still hosted.
Your builds are heavily protected. Server backups occur frequently off-site to AWS. High Performance: 1Gig uplink, NVMe, databases, and plenty of dedicated cores and memory.
You can be confident that you will not lose your time investment building here.