I'm facing the same problem. After changing the numbers in the Exel table, the binoculars and periscopes no longer worked, and the screen began to flicker. The following method helped me.
Instead of opening the file as a table, I opened it using the WinRAR archiver. After that, I changed the required numbers in the document to: "IlluminationConfig\xl\worksheets\sheet1.xml ". By saving the modified file and updating it in the archive, the game started working normally. If you encounter this problem, re-subscribe to the mod to get a new working spreadsheet, and edit it using the archiver.

@Etyneo LibreOffice is known to have issues saving xlxs in a way UBOAT can read. I use Google docs and export as xlxs, personally.

Ok, looks like LibreOffice is not saving the xlsx correctly and thereby making it unreadable by the game. Guess I get to alter the source instead.

I did find the cause of my issue, just trying to figure out how to solve it.

Found an error in the logfile indicating that the mod was unable to read the Red from the xlsx for some reason. Might also have applied to the other color values. Using the default version of the xlsx that comes with the mod does work. Just trying to figure out how to alter the values without breaking the game's ability to read the values.

@Etyneo Nothing is left in the save file with this mod.

Does this leave anything in the save file? While adjusting the numbers in the xlsx and loading the game over and over again to find the right values for the color I want, the game started giving me a flickering black screen when loading into the UZO, Periscope, etc. I'm trying to troubleshoot. I was using the More Accurate series of addons for the Periscope (Wider version) and the UZO/Binocs. However, removing these does not get rid of the flickering black screen issue.

Ok I thought I might have made a mistake.
I'm happy as it is, at night I now have a very pleasant slightly bluish crosshair color. Great!
Many thanks for the great modifaction

@R.Rohleder That's an intentional design choice on my part for the periscope mod. I read somewhere that only the lines were illuminated on sights from the era, so I've carried that over from my other optics mods. Tbh, I don't personally use the "More Accurate" series, so I am more than open to making changes on it.

A question for DarkRaven. I am using the great modification "More Accurate Periscope Sights - WIDE" and have adjusted the crosshairs brightness and color to my liking. Unfortunately the numbers on the X and Y axis are not illuminated. Is this possibly due to the new patch, am I perhaps doing something wrong, or is it not even possible with the Sights Wide version?

@Airplayn The mod literally only changes the reticule color. You can look at the code used yourself. But I'll investigate further. There was major patch a few days ago, maybe loading and old save into the new patch has caused an issue.

I know your mod just changed RETICLE COLORS but I noticed in your sample pictures the night is PITCH BLACK. I wondered whether you ,might have MUTED the brightness of the actual night vision to make the reticles stand out. The ONLY time I see the night sea and sky id when I'm viewing a scope WITHOUT the reticles your mode makes. These make me wonder. Thanks for your effort and time.

I'm not complaining I appreciate your work, I'm just frustrated. If I look at the sky through the scope on small view everything ios fine. But if I look through the binoculars or UZO or wide view it's pitch black. Target markers are there but can't see target starts or water. Uninstalled wide scope etc. All I know is that it happened right after I activated the mod. You seem an expert at this illumination issue. Can you suggest a file position that I could go to and troubleshoot this? I have a nice career established and hate to trash weeks of achievements to restart. I'll be happy to give you a "reword" emogi of your choice and thank you publicly. For direct contact I'm at AIRPLAYN@hotmail.com, Thanks Pal.

This mod doesn't affect nights in anyway. Only the color of the sight at night. Your princess is in another castle.

Tried mod and now ALL my nights are pitch black with no visibility/ It's screwed up my long career game, can't get rid of it, HOW do I get my nights back? I've wasted two days fighting this.

What are the figures to change it to the tan/yellow colors so I can edit the datasheet file to change it to that preset

Mod, is in fact, currently working.

Just to confirm, is in not working or the mod loader claim it's outdated?

@stullenandy Entschuldigung, aber mein Deutsch ist nichts Besonderes. Sie sollten die Werte von Grün und Rot vertauschen und dann alle Zahlen außer Alpha mit mindestens fünf multiplizieren, sonst wird es sehr dunkel. Die bereitgestellten Screenshots zeigen diese Werte multipliziert mit fünf.

Moin Moin ,es tut mir leid aber ich würde gerne das Fadenkreuz in die Farbe Rot verändern.Aber verstehe nicht was ich wo in der Confic Datei eintragen muss damit das Im Spiel dann auch Rot erscheint...Grrr bitte er klärt es mal einem alten Kerl wie mir. Wäre narürlich der Hammer wenn es am Periskop einen Gemoddeten Schalter gäbe wo man die Farben durchschalten könnte

Looks nice! Great job

Thanks mutch better for the eyes,now we can see!!

@Eridano Just multiply the vanilla default values by 4. They are listed in the config.

Thank you vm, I was waiting for this!

Thank you very much for that my eyes doctor also ordered me to thank you ^^

Many thanks for this mod!
what Is to be changed for green intensity x4?