I search replacement of Cherry Tree

Hello,
I use Cherry Tree under Kubuntu 18 and wonder are there some replacement of it with features:

  1. Similar tree view organization
  2. In one page search without modal dialog (like kate does)
  3. text validation. At least english, but if can also work with other languages - very nice
  4. Import from Cherry Tree CherryTreeFile.ctd
  5. Working with rather big files. Now my CherryTreeFile.ctd has size about 12Mib and it seems rather slow…

Are there something like that ?

Thanks!

I found KeepNote and tried to test it. But I did not find if there is a way to import into KeepNote from Cherry Tree?