Bulk Delete Nest Albums in Photos by Pattern?
Launch Script Editor and create a new script.

Deleting folders named ".@_thumb"

Copy and paste the following script into Script Editor.

use Photos : application "Photos"


run Photos

recurse(application "Photos")
repeat with F in flatten(result)
    try
        delete F
    end try
end repeat


to recurse(_X)
    set _A to a reference to every folder of _X
    if not (_A exists) then return {}
    return (_A whose name = ".@_thumb") &amp; recurse(_A)
end recurse

to flatten(L)
    local L

    if L = {} then return {}
    if L's class ≠ list then return {L}
    flatten(item 1 of L) &amp; flatten(rest of L)
end flatten


Run the script (⌘R).

The second issue you mentioned is trickier because of a bug in AppleScript that returns an incorrect reference to newly created albums.  At the moment, I'm not sure of a workaround, but I will have a think and update this with any thoughts I glean.