i10:
First generation (2008-13, but there are some listed as 2007 and I believe a couple outside Europe listed with more recent years) is [PA] and origin India. Also, category is supermini (there are some listed as hatchback).
Second generation (2014-19) is [IA] and origin is Europe, built in Turkey, so made for EU tag is redundant. Category Supermini. I see there is one listed as [BA]. I believe it is a mistake, or is it a reason?
Both of them have some examples listed without year and a chassis code, so I believe they have to be sorted manually? Also is to check if there are some second generation ones outside Europe that are actually indian-built and origin models.

Grand i10:
2014-19 are [BA], and origin India for both the sedan and the supermini.
There is a single 2020 model, which sould be [AI3], not [AC3] if I understand correctly?

Xcent:
All are 2014+ [BA], and they are already set with origin India.

We have no Grand i10 Nios for now if I'm not missing anything.

i20:
They are all Europe origin.
First generation (2008-13) is [PB]
Second generation (2014-19, also i20 Active) is [GB]
Third generation (2020+) is [BC3]

Elite i20
It should be Indian origin if I understand correctly. All the ones on the site are [IB].

We haven't yet any Indian i20 [BI3].

Well, I see that for some other models we have mixed situations:

ix20
The origin should be EU, as it's designed by Hyundai Europe in Germany and only sold in Europe. Chassis code [JC] is missing from most entries, and a couple are listed as hatchback, but it should be a Van/MPV

Bayon
We have only one so far, which is listed as origin South Korea, but it should be origin EU just like the ix20 (designed in Europe and made for European market). Missing model code is [BC3] and it's built in Turkey

i30
The i30 should have origin EU, as all the generations were engineered by Hyundai Europe in Germany. More than a half of the entries are still listed with South Korean origin, though. Assembly in Czech Republic is confirmed for all the EU-market units. Not sure about the origin of units for Australia/New Zealand, while the North American Elantra Touring and Elantra GT are sourced from South Korea, but being essentially the same identical car as the European i30 I think we should keep the EU origin also for them.

i40
The i40 [VF] is a rebodied derivative of the global Sonata engineered by Hyundai Motor Europe GmbH in Germany, and it's sold mainly in Europe and Oceania, but not in home market South Korea, despite being assembled there. I think EU origin could be appropriate also here (some are already listed this way).

Creta/ix25
According to the site of Hyundai Motor India Engineering, the Creta models are to be credited to them https://hmie.in/company/about-hmie. The entries listed so far have mixed listings, including South Korea and China.
Codes for the first generation should be [GS], with [GSb] for the Brazilian-built model (from 2017 on, still on sale together with the new model), which seems to differ only by the engine options. The badge-engineered ix25 for China (2015-19) is reported having the code [GC].
For what regards the 2nd generation, the codes should be:
[SU2i] for the 2020+ Indian model (sold also in Mexico and Brunei since 2021 and in South Africa until 2022)
[SU2c] for the Chinese 2019+ ix25 (which has different front and interior)
[SU2r] for the 2021+ Russian-built model (with specific front)
[SU2b] for the 2022+ Brazilian model (based on the Russian one but with flex engines, still sold alongside the old model)
[SU2id] for the 2022+ Indonesian-built model (with another specific front, exported also to Middle East, Africa and some other neighbouring South Asian markets as like Vietnam, Thailand and Malaysia in addition to South Africa starting from July 2022)
A possibility could be maybe, considering also the different model codes, to give to the ix25 Chinese origin considering the many differences?

Eon
All the Hyundai Eon (Atos Eon in some North African markets) are listed with South Korean origin, but it’s an Indian engineered car. Not sure about the model code

Getz/Click
This is a border-line case: the car was one of the first models engineered by Hyundai’s R&D centre in Frankfurt, but the car was built and sold also in South Korea. One reference: https://carpart.com.au/blog/hyundai-getz
Not sure how this should be handled.

It appears the i30s sold in Australia and NZ were sourced from South Korea, except the rare 3-doors, according to this comment by MisterZ: https://imcdb.org/vehicle.php?id=1172160
I believe that is the only 3-doors listed in Oceanian location.

About the Getz/Click, I'm wondering if there was really significant imput by the Euro R&D center, which was just opened if I understand well what I'm reading? Personally I'd leave it as origin South Korea. Also we'd have to revert the model code to TB I believe.

And yes, I agree too with the [GB] i20 being 2015MY, also here first units arrived in December at least, if not directly in 2015

I forgot to mention the Venue. There are two models available: the global [QX] and the Indian [QXi], which is shorter as usual. Also here, I'm not sure if the [QXi] deserves an Indian origin, while the [QX] is for sure a South Korean design.