Hello. First of all, I would like to thank Vlad for this mod.

My problem: I might have found bug today. I have Dar in my party and when he's injured and I save the game, then I load it, Dar is automatically healed immediately after loading, but not always, it's just... often. I have never noticed this problem before, also I haven't seen this problem on other NeJ NPCs.

Note: I play NEJ2V693, I don't know if this problem appears in newer version of NeJ too.
(Excuse my English, I am not native English speaker)

By the way, here is my weidu.log:

// Log of Currently Installed WeiDU Mods
// The top of the file is the 'oldest' mod
// ~TP2_File~ #language_number #component_number // [Subcomponent Name -> ] Component Name
~SETUP-BDTOBV16.TP2~ #0 #0 // MULTI-STRONGHOLD. All the warrior classes (fighters, rangers and paladins) and monks may get the De’Arnise Keep as their stronghold in addition to another stronghold which is accessible according to their class. Also all dual- and multi-classes have no restrictions to the number of strongholds they may obtain.
~SETUP-BDTOBV16.TP2~ #0 #1 // GRAND MASTERY FIX. This fix originally created by James Schumacher you may get from various sources including Baldurdash tweaks and cheats. It fixes the weapon proficiency table for fighters according to the original D&D rules implemented in BG1 and IWD. If you have not installed it yet I would strongly recommend to do so.
~SETUP-BDTOBV16.TP2~ #0 #2 // BONUS MERCHANTS. These are the two bonus merchants from the original BioWare Collector’s Edition CD.
~SETUP-BDTOBV16.TP2~ #0 #3 // Improved Nymph (Woodland Being) Script by Goeran Rimen
~SETUP-BDTOBV16.TP2~ #0 #4 // Dual Wielding Fix for Rogues by aVENGER
~SETUP-BDTOBV16.TP2~ #0 #5 // Baldurdash Fix Pack for ToB, v1.6 WeiDU
~SETUP-BDTOBV16.TP2~ #0 #6 // Textupdatepack -> Baldurdash English Text Update Pack for ToB, v1.4 WeiDU
~SETUP-IMPROVEDANVIL.TP2~ #0 #0 // Improved Anvil for SOA & TOB
~SETUP-TS.TP2~ #0 #0 // TORTURED SOULS v6.11
~SETUP-TS.TP2~ #0 #3 // AREAS & SOUNDS. This component is required to play the mod.
~SETUP-NEJ2V691.TP2~ #0 #0 // Never Ending Journey Second Edition v6.91
~SETUP-NEJ2V691.TP2~ #0 #1 // Continuous and Custom Kit Imoen
~SETUP-NEJ2V691.TP2~ #0 #3 // Priest of Sylvanus (Druid) Kit and Improved Character Jaheira.
~SETUP-NEJ2V691.TP2~ #0 #6 // "Firewalker" Shar-Teel (custom kit and continuous character)
~SETUP-NEJ2V691.TP2~ #0 #7 // Additional content for Part II (beta)
~SETUP-NEJ2V691.TP2~ #0 #8 // Frostbite Animation (Turns a big wyvern into the frost wyvern. You may install and uninstall this component at any moment in the game.)
~SETUP-NEJ2V691.TP2~ #0 #12 // Areas & Sounds (This component is required to play NeJ2!)
~SETUP-NEJ2V693.TP2~ #0 #0 // Never Ending Journey Second Edition v6.93 (Patch)

Surely, it's not a bug, and cannot be considered as a bug. There may be several reasons: items, high constitution stat of Dar or something that Sikret is aware of.

Okay, thanks for a quick response.

You'll find the same thing occuring with Kagain. Dar's Con = 21. With a constitution score of 20 or greater the character will begin to naturally regenerate. You'll notice this occuring when travelling between areas as well due to the elapsed game time during travel.