Tested the issue on chrome version #70.0.3538.110 and reported chrome version #71.0.3578.80 using Windows 10 by following below steps.

Steps:
=====
1.Launched chrome.
2.Typed facebook.com(which has support tab to search) and pressed tab.
3.Changed the keyboard preference to Korean.
4.Typed the letters "w,e,r,t,y" from the keyboard.
5.Unable to find any difference in behaviour in both builds.

Attached screenshots for reference.
@reporter: Could you please review attached screenshots and let us know if anything is being missed here. Requesting you to provide sample URL in Korean so that it would be really helpful in further triaging of the issue.
Thanks.!

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	914339_M70.PNG 34.9 KB View Download

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	914339_M71.png 66.5 KB View Download

This is a really painful bug for me.
Each Korean character consists of multiple alphabets.
It appears when using a tab to search, chrome can't construct the first character.
In your fourth step, try "r", "j", "a", "t", "o", "r" instead.
It types "ㄱㅓㅁ색" instead of "검색".

I'm not sure when this bug appears, maybe chrome 70 has the bug as well.
FYI, I'm using chrome in English locale on Mac.

facebook.com with typing "w,e,r,t,y" works well for me.

but if you want to make words in korean, you have to type vowel and consonants.

typing "w,e,r,t,y" is "ㅈ,ㄷ,ㄱ,ㅅ,ㅛ"  "ㅈ,ㄷ,ㄱ,ㅅ" is one of vowel "ㅛ" is one of consonants.

try any "vowel + consonants" type words.

facebook in korean is 페이스북

try "v" "p" "d" "l" "t" "m" "q" "n" "r" in facebook search.

right thing is "페이스북". but chrome tab search makes "ㅍㅔ이스북"

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	typing.gif 25.6 KB View Download

Thank you for providing more feedback. Adding the requester to the cc list.

For more details visit https://www.chromium.org/issue-tracking/autotriage - Your friendly Sheriffbot

For your test, I can type well also.

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	크롬.png 14.6 KB View Download

This issue seems to be similar to Issue: 896962, hence merging into it and marking it as Duplicate.
Note: Feel free to Un-Dupe it if not the case.

Thanks!