@Jerry K. - Howdy Jerry, thanks for coming into conversation and I saw your forum & blog posts too. I hope you're enjoying life in AZ over IL.
1) Value of tax liens on foreign owner over several parcels is less than lawyer would charge for consultation. I'm raising this question to few counties to get a simple answer which would be I would still have to use Certified Mail without getting it accepted in foreign country or use Fedex with signature confirmation which may or may not be accepted at the foreign owners address. If I don't get an answer I'll just skip parcels owned by 1 particular foreign owner and get a few parcels in exact same subdivision that are delinquent long enough and owned by USA owners.
2) I meant that in 2018 there was a lien placed on the property at statement of taxes and for 2019 & 2020 it shows taxes unpaid. So whenever 2018 lien was placed exactly (I don't remember exactly which parcel I was referring to since I've processed hundreds more since) it would be 2021 (+3 years) when it would be eligible for foreclosure.
I guess going back & more things I've learned now my question would've been better phrased - If there is first placed lien which is close or beyond 3 years redemption period would other year of unpaid taxes would have to be turned to liens or could be paid off to satisfy redemption at +3 years. I've already learned the answer to this.
I'll take your advice and skip parcels where there is still unpaid taxes for 2019, 2020 in general but I do want to confirm it with you if I'm understanding your logic correctly in this type of scenario

It shows interest for 2014 / 2015 which is as far as history goes. My understanding that 2016 lien was placed on 2013 taxes and that explains that 2014,2015 have small interest from county but not tax lien interest. At 2016 /2017 / 2018 liens are created and shows 16% interest from tax lien. With first tax lien placed in 2016 this parcel is eligible for foreclosure. If I foreclosure it I would still be required to pay all unpaid taxes. Wouldn't it be better to pay them off before they have any interest and / or tax lien interest of 16% added to them. I understand that in scenarios where property is not eligible for foreclosure I wouldn't want to pay unpaid taxes yet and better to wait for them to convert into lien and time would be beyond 3 years from initial lien.
As you can see from this example I'm hunting down very cheap properties with very cheap yearly taxes and tax liens. For most these properties are of no value, including original owners and I feel most have abandoned them. I am also aware that there is no way to get title insurance on it for anyone who would want to get loan to build a home due to the type of the deed that is given on it. For me its obviously better to try to acquire parcel for under $200 each via tax liens + cost to send few certified letters / post ad in newspaper or purchasing property from the county at $600-750 when retail prices are $1500+ for lots that don't have as good of a view as the ones I've found. I'm counting on several photographers that I know to flip some of the lots I get with good views from the start as well as recruited few friends who want to start flipping land within their communities. I'm transparent with everyone that this is not the type of community where most people develop, its more of complete ghost town and explaining to them that whoever they resell it to would not be able to get a loan to build a home. Knowing this information they're targeting FOMO kind of crowd. They buy few parcels from me at discount from expected retail price (at one or few different subdivisions / geographical locations) and start bragging to their friends / family that they're following my steps in investing & flipping vacant land. We live in a large city where most people either rent or own apartments. There are many that never owned piece of land in their life and when they hear about others who are investing into it affordably they get FOMO. About 15+ years ago there was a local marketing campaign to sell land in FL and many people jumped on while some missed out. One of my friends referenced someone he knew who bought FL land for $5000/ 5 acres and there were some swampy parts. He paid $500 to have some sand poured over few patches and flipped it for $10,000. My friend wished he would've done the same and now I'm offering hand selected parcels at below retail cost and he wants to jump on the opportunity to resell to others. For non photography people I've found lots that are closer to center of town in more developed parts of subdivision and do have direct or nearby power.
Overall I'm continuing to analyze more data and finding more opportunities in different counties. I've decided to narrow down my first round only to one county and just near one town where there are few subdivisions. I'm getting 11 lots with nice views, direct road access and will keep 3 best for myself and flip 8 to photographers. I'm getting only one small lot in developed part with direct access to power and for now skipping few others that I've found with power nearby. This lot will be offered to my non photographer friends to flip. At the same time I've identified several lots that are just as good as one I'm purchasing and in some cases better that are available collectively for under $1000. All of them have first liens placed starting in 2016, 2017 and would be ripe for foreclosure. One under $200 tax lien on nice double lot with lien beginning in 2016 belongs to a trust and I will avoid purchasing the lien and instead wait for county to foreclose it and offer it via back tax lot purchase. My average cost per acre is $436 on purchases where I see retail prices start at $1500 for just any lot in same subdivision which is far away from the views and may or may not have road access. Easily accessible lots with similar views slightly further away from my lots are offered at $2500+ There is a lot of room for me to make 3-5X return on small handful of lots I'm getting in round 1. I'll post an update on my journey as it develops.