Well, if you ever get back into Civ6 modding? I have an idea of a slice of life update to improve the mod.
https://gtm.steamproxy.vip/sharedfiles/filedetails/?id=2967632702
Pings on hills that have the effect saying "+1 RAN" being autobuilt into the hills, if an building or improvement takes away the hills being, well, hills. the marker will go away. If the obstruction is removed it appears again.
Of course it might require an autoping script, and I don't know if that's possible vanilla.

I honestly wouldn't know, i've been away from civ6 modding for over a year now.
Just take a look at my code (it should be very similar to what you want) and adapt to what you need,

At least the range should work.

You basically should have to create a new class with the bonuses and then assign it to the units you want.

Stuff that i added (like the new class) should have a prefix/sufix "JMG" so you can cleary see what is new.

@56Mumia: I was thinking forests / rainforests could add +3 to range for ranged units and +5 defense. Would that be possible to make?

Nice mod, so simple so obvious so good. I whish Watchtowers would do the same.

Hey Olafr_the_Viking, i'm glad you like the mod.
Thank you for sharing the incompatibility so it can help anyone having the same problem.

I found the incompatibilty, and want to share it with other users; it was the "Enhanced Civil Infrastructure" mod (that one has a work-around to open up for building canals on hills), it seemingly alters hills in such a way that this mod breaks. And this mod is SO much better, so it is an easy choice. Looking out for hills on the battlefield to get that sweet range bonus to for example reach the city with siege equipment is one reason, buffing slingers to make slingers far more fun is another, planning the attack movement of troops based on where and if there are any hills present, and seeing the AI sometimes using it really well (shooting me from afar), is just some examples of how this fabulous mod works. This mod is essentially a must have for me now, it is actually one of my favorite Civ 6 mods and features - so it is an easy choice to kick the other one, and ensure this gem still functions.

Hello! I am trying to get this mod to work again, but it seems to have stopped working somehow for me. It might be an incompatibility in my mod list, but it used to work ok with the same mods, and I have not been able to locate the culprit yet. Anyone else having had such issues with this mod lately?

Thanks. Appreciate that you mentioned me.

Hi Junky, thank you for your suggestion.
The mod has been updated.

I recommend to use this sql for compatibility with all other mods that add units:

INSERT OR REPLACE INTO TypeTags (Type, Tag) SELECT
UnitType, 'CLASS_LAND_RANGED_JMG'
FROM Units WHERE PromotionClass IN ('PROMOTION_CLASS_RANGED', 'PROMOTION_CLASS_SIEGE','PROMOTION_CLASS_RECON','PROMOTION_CLASS_MELEE','PROMOTION_CLASS_SUPPORT') AND Range > 0;

Hi there, sorry for the delay.
I don't remenber exacly to witch units i added the range but i believe it was all vanilla units with range (including melee units that have a ranged attack).

Sure, you can upload it.
I'm glad you liked it.

I made a patched version that seems to be working, where the unique units from Steel & Thunder are added to the list to give them the same ability to get range increase on hills. Is it ok that I upload it as a patched version here on Steam Workshop - with full credits to you as the original author, or do you prefer that it is done otherwise?

Sorry for my frequent messages/updates, but now I learned how to open the SQL from the mod file to see the text for myself, and it looks like it should work for bombard class as well, only I used Alexander, and he had the "Ballistra" (replacing catapult, from Steel & Thunder), and that unit is not included in the code - so I'm gonna try my luck to add that unit to the code, but from the SQL file, it looks like the rest of the regular bombards are mentioned in there - which is awesome, because I think this concept will make siege warfare so much more strategic, finding the hills to position the artillery from one tile outside the city retaliation range. And I am really looking forward to see if maybe the AI can become a little better at taking walled cities with this range help, as well (using another mod that nerfs walls to half their usual HP, and hoping that these two mods together can help AI to conquer more).

Have checked this mod in a few short games now, and as of 8th December 2021 it seems to be working. Both slinger and archer got range increased from 2 to 3 upon going up on a hill (and correctly reduced to 2 when going down from the hill again), but unfortunately, the catapult did not get the same increase. So I was wondering; do anyone know how I could add that mechanic, so that the bombard class (catapult, trebuchet, bombard, ballistra, etc) could get this same range increase when they stand on top of hills? Thanks in advance for any help, and thanks for a nice mod - very cool idea, should have been in the base game!

And: Does it work for modded units (i,e, Steel & Thunder) as well, or only Vanilla units?

Does this work for both ranged units (i.e. Archer) and siege/bombard units (i.e. catapult), or only the former?

If its just the txt, its probably a load order problem if you use other mods, try increasing the <LoadOrder> in the file HillsBonusCombatRange.modinfo.

Other than that, at the moment i dont play Civ6 anymore, so will probably not be updating this mod if another update come along.

If anyone has this problem or notices other bug please let me kmow.
Thanks

Can you update it, his display problem, can't effectively display the description, there will be LOC and so on