Not a reviewer, but I decided to take a look in the CS and OpenMW anyhow, just to see if I can help.

It's a very simple quest indeed (your last file), but most things seem in good order. The is, however, one breaking issue and a few smaller ones:

• What breaks the quest currently -- Sharli is checking for Journal EN_Show = 20 for her dialogue, but Gih-Me only gets you up to Journal 10. Hence, it's impossible to complete the quest, save for killing either Sharli or Gih-Me.
• Gih-Me has a ridiculously high level (45) and is a Battlemage service provider. This high a level should be reserved for the rarest and most high-ranking characters. Battlemages, too, tend to be very rare in the Morrowind province and their presence must be well-justified.
• A disposition requirement of 80 (which is needed for Gih-Me to fire his greeting) seems awfully high to start such a relatively low-level quest. Up to your taste, but I'd lower it a little. At least you should add a hint that the character has a quest for you at a higher level of disposition, so that players wouldn't miss the content.
• Another matter of taste, but I'd add another entry to both Gih-Me and Sharli for the "Sharli" topic after the first time you ask them about it. Sometimes the player will accidentally click the dialogue window closed and it'll be frustrating if the topic is just gone the next time.
• The identation in the scripts is not correct -- make sure that all `If` and matching `endif` statements are at the same level of identation and that nested blocks are uniformly indented. Like this:
  
• You have a space on the inside of the parentheses, which is good, but most scripts usually have a space between `if` and the starting parenthesis, too. Meaning `If ( OnDeath == 1 )`, not `If( OnDeath == 1 )`. Though this probably isn't an issue for the game, at least according to MSFD, it is still better to be consistent with other TR scripts.
• The greeting 5 entry for Gih-Me: "Well, have you found out what happened to Sharli?" does not appear, since you have two filters -- one checking for Journal En_Show >= 10, the other for = 0. Both of these can't be true at the same time, so the dialogue does not appear.
• After you fix the above point -- you should add a filter to the same greeting to remove it after Journal EN_Show >= 100, so that Gih-Me wouldn't keep asking you about Sharli forever, even after you finished the quest.
• Totally not sure, but I worry that if Sharli doesn't have "Corpses Persist" checked, perhaps the 'Dead >= 1' filter in Gih-Me's dialogue will not work correctly? E.g., once the corpse is unloaded from the game? I may very well be wrong. In any case I'd avoid any potential issues by updating the journal once Sharli dies and only checking for the journal entry in Gih-Me's dialogue.

Otherwise, the dialogue has no language or style issues that I could see and the file appears clean.