I checked the historical available versions and found that only up to R296 is retained. I don't oppose your upgrade to SDK2, but can you ultimately keep a version that still supports SDK1? I don't need new features, but I simply cannot update all projects using SDK1 plugins one by one.
Therefore, could I request that you retain a version that supports SDK1 for the sake of maintaining old projects? For example, the author of "ProUI" has stopped maintaining it, and while I can modify the plugin myself to ensure my old projects run properly, it is nearly impossible to remove ProUI from all old projects and replace it with built-in components to achieve the same functionality.