Ain't a UI, nor does it do much editing for you.
It just supports you by automating routines and with creating additional save games in ironman runs.
Use at your own risk - the scripts are neither very long nor complex, just read them if concerned...

Requires python & Windows.

I just created it for myself and provide it to anyone who wants it. Maybe someone finds it useful, maybe not. Just be nice anyway :)

What I use it for
1.    Getting a peak at the created galaxy with observe, just checking where the caravaneers are or where earth is.
2.    Changing coordinates of the later created coordinates like precursor homeworlds or Rubricator world because I just can't stand overlapping hyperlanes.
I still have to reload the savegame a lot because coordinate editing is more or less try and error.
3.    Changing the precursor event to cybrex because Cyrbrex are cool and machine empires love cybrex artifacts :D
4.    Making my red racket species real relatives of the rackets (easy to fuck up the game when you edit species by try and error xD took some time to get the job done) >>if you want a tip I am happy to help :)

README
USE AT YOUR OWN RISK!

REQUIREMENTS
1.    Windows operating system (only tested with win10)
2.    python 3.X (f.e. 3.8.0) https://www.python.org/downloads/
3.    7z https://www.7-zip.org/7z.html

GETTING STARTED
1.    Start/Have an ironman run in Stellaris.
2.    put BAT files & TL_SET_scripts into the folder of the savegame you want to manipulate:
    usally sth.  like ...\Documents\Paradox Interactive\Stellaris\save games\<your empire's name>
    -->there should be the iroman.sav file

USAGE
TL_0_create_observe
    > creates an observe(.sav) savegame that is no ironman save and therefore allows console commands
    >    1.    load the "observe" savegame
        2.    open console by pressing "^"
        3.    type "observe" and confirm
        4.    look what s**t the Stellaris engine created this time
        Note: let some time pass to see all hyperlanes
        5.    delete the savegame in Stellaris then start anew ->the scripts will still be in place for this empire setup
    > observe(.sav) is not ment to further play with
TL_1_save
    > creates an ironman-<game year>.sav file as save
    > creates/updates ironman-backup.sav to the current gamestate
TL_2a_zip_unpack
    > unpacks the ironman.sav file into TXT files to be manipulated
TL_2b_zip_repack
    > repacks the TXT files into a working ironman.sav
    > !!! overrides ironman.sav !!!
    Note: can only work if TL_2a_zip_unpack was run first
TL_3_restore_last_backup
    > replaces ironman.sav with the ironman-backup.sav gamestate (last save)
    Note: for restoring one of the other files replace ironman.sav with it (delete; copy+paste; rename)