[BUG] additional armor modifications on helmet aren't displayed correctly or shouldn’t be selectable, Chemical Protection is missing in general (or works different)

[Knakriktsur]

Chummer 5.225.456

Describe the bug and To Reproduce in one
There are some different bugs reported in the whole text. For my Char I have the problem that only fire resistance was counted on the print sheet. So, I made a new Testchar to verify. I added an Armor Jacket (Capacity 12) and a Custom Ballistic Mask (Capacity 8). Then I went to "Street Gear" -> "Clothing & Armor" and on the right to "Spell Defense" tab. At "indirect Soak" it showed 14 (Body was 1 for test) but Armor Jacket (12) and Custom Ballistic Mask (+2) Should be 12+2=14 + 1 from Body so 15 (which would be wrong)? I'm not sure if the +1 body is correct there and the tooltip shows 13+1?

Then I added to the Armor Jacket "Fire Resistance (Rating 3)", "Nonconductivity (Rating 3)", Radiation Shielding (Rating 3) and Chemical Protection (Rating 3)", sums to 3+3+3+3=12 for a capacity of 12.
To check I went to print sheet and in the preview at “RESISTANCE” it was as followed:
Radiation 5 (was 2 before so +3 from Radiation Shielding (Rating 3) worked)
At "RESISTANCE - DAMAGE TYPE STUN PHYSICAL" it was as followed:
Damage 14 14
Fire 17 17 (+3 added)
Cold 14 14
Electricity 17 17 (+3 added)
Acid 14 14 (shouldn’t that also be 17 or doesn't Chemical Protection (Rating 3) protect against acid?)
Falling 14 14

And then I also added to the Custom Ballistic Mask "Fire Resistance (Rating 2)", "Nonconductivity (Rating 2)", Radiation Shielding (Rating 2) and Chemical Protection (Rating 2)", sums to 2+2+2+2=8 for a capacity of 8. So, both armor are modified now.
To check I went to print sheet and in the preview at “RESISTANCE” it was as followed:
Radiation 7 (2 standard, +3 Armor Jacket +2 Custom Ballistic Mask =7, should it be highest value or added?)
At "RESISTANCE - DAMAGE TYPE STUN PHYSICAL" it was as followed:
Damage 14 14
Fire 17 17 (+3 added from jacked, highest value?)
Cold 14 14
Electricity 17 17 (+3 added from jacked, highest value?)
Acid 14 14 (shouldn’t that also be 17 or doesn't Chemical Protection (Rating 3) protect against acid?)
Falling 14 14

And then I removed the Armor Mods from the Armor Jacket and only had the one of Custom Ballistic Mask.
To check I went to print sheet and in the preview at “RESISTANCE” it was as followed:
Radiation 4 (2 standard, +2 =4) So Radiation protection works?
At "RESISTANCE - DAMAGE TYPE STUN PHYSICAL" it was as followed:
Damage 14 14
Fire 14 14 (Shouldn't it be +2 added from Custom Ballistic Mask?)
Cold 14 14
Electricity 14 14 (Shouldn't it be +2 added from Custom Ballistic Mask?)
Acid 14 14 (shouldn’t that also be +2 or doesn't Chemical Protection (Rating 2) protect against acid?)
Falling 14 14

I'm not a 100% sure if you can add “elemental protection” in helmets, but if you can't you shouldn’t be able to select them there or maybe for house rule add an info there that that is not "standard" behavior. Hope you can understand everything I mean, if not feel free to ask or discuss. Thank you :3

[RiskyUmbrella]

I don't think the Helmet should add to your resistance.
SR5 pg. 438
Shields may be upgraded with the chemical
protection, fire resistance, and nonconductivity armor
modifications and have a Capacity equal to their Armor
Rating for this purpose.
Helmet: Helmets come in a wide variety of shapes
and sizes and protect your noggin from trauma. Helmets
have Capacity 6 for being tricked out with accessories
like trode nets and vision enhancements.

Also Acid damage is different from toxins, and chemical protection doesn't prevent acid damage SR5 pg. 170
ACID DAMAGE
Acid damage is Physical. In addition to its normal dam-
age, it also reduces the rating of any Armor it hits by 1.
If the acid isn’t removed from the target (by washing it
off, or because the acid is from a spell and evaporates
into mana after the spell ends), then the acid continues
to burn. Each Combat Turn the base DV of the acid is
decreased by 1 and damage is applied again. The acid
also continues to burn through armor reducing the tar-
get’s Armor rating by 1 until the acid is removed, neu-
tralized, or loses all its base DV. The Armor reduction
should be applied to worn Armor first but could be ap-
plied to Armor accessories (+Armor items) if the gam-
emaster allows.
At the gamemaster’s discretion, acid can also create
Light Smoke conditions in an area around the target

Acid Damage is the only elemental damage in core with no direct link for an armor resistance mod to counter it.
Chemical protection applies to contact vector toxins SR5 pg. 408
Most contact vectors also have an inhalation effect, this is where a built in respirator to your helmet would apply resistances to the breathing test. you can add a respirator to your helmet.
Chemical Seal is only applied to Armor, it costs 6 capacity but includes the air supply, when paired with a helmet / mask that covers the whole head, can be used to provide 1 hour of air at a time, allowing for contact, and inhalation immunity.

It is likely that the reason you can see the armor upgrades is because helmets and shields are in the same category, but armor resistance modifications are only honored by the shield. I think the fix here is to prevent resistances from showing up as options for helmets.
If you wear armor under your jacket (Form Fitting Body Armor, Armor Clothes, etc) you can add to additional resistances and those won't stack, but can add a new protection, just keep in mind that you can't wear 3 jackets, so consider a bit of realism, a full body set of clothes under a jacket is fine. 3 jackets isn't fine. e.g. Fire resistance on Jacket, Non Conductivity on Clothes. Highest resistance applies if they have duplicates. So nonconductivity 2 is replaced by non conductivity 3+. Similar to how armor ratings dont stack. a 12 armor rating Jacket doesn't add a 7 rating clothing, highest is honored.