Welcome! Some comments on the scripts,

MelzacScript
doonce value is not changed so the condition will never stop (also you could do that addtopic in the creature's greeting if you wanted and the topic would appear on its second dialogue entry)

other scripts: FYI usually OnDeath is the more reliable function to use instead of GetHealth==0

Generally, I recommend using spaces consistently and more, there are rare compiler or engine errors that make me afraid of things like if( player->GetArmorer>=required) instead of player->GetArmorer >= required , but if it works it works...

dialogue result scripts: FadeOut doesn't work in the result
FadeOut 1.0
Journal Forging_Centurions 20
player->removeitem misc_dwrv_artifact50 1
player->removeitem misc_dwrv_artifact00 1
player->removeitem misc_dwrv_artifact60 2
player->removeitem ingred_scrap_metal_01 4
player->removeitem misc_dwrv_coin00 10
FadeIn 1.0
 adding lines between FadeOut and FadeIn isn't going to make it fade out then fade in, only FadeIn will turn the screen black and fade in

Dialogue has variants for player race but Not Race conditions are for the speaker and it's a creature so these are always true, for the player's race you usually need Global PCRace conditions,
and if they worked there would be an issue with the logic of conditions for player being three different races at the same time, instead you could add if ( PCRace ... conditions in the results of the previous dialogue entry and give different choices depending on race. ('if' conditions work in dialogue results just like they do in compiled scripts)

latest rumours topic:
the rumour 'up at the manor' is spoken by NPCs in the manor, the journal says 'local Scout' which the dialogue didn't say,
more importantly this quest hook is too aggressive as the rumour overwrites everything in this topic even after the first time and never stops even after the quest is complete,
it opens a quest title in the player's journal whether the player wants to do it or not, and even talking with the NPC in the manor and refusing can't close it, but the better way to do it if a journal entry is given by a common topic like this is to mark that first journal with Finished and mark the next entry with Restart later to open the journal when the player does look for the quest NPC,
saw few typos - 'go recieve' receive, 'head east follow the southern coast', 'your hard work Outlander' would have a comma

However you don't need to update your file for TR (tho you probably will if you plan to release somewhere) but since you clearly know the basics already I recommend looking at the claims browser  and if anything interests you popping on the discord to say you want it