That “latest” tech of 0W-20 is useless for an engine as old as R18 especially in our warmer climate. An engine that was introduced in 2006. That’s 18 years ago!
More importantly, the R&D and oil requirements that went into developing R series is even older. GF5 will provide same protection as GF6 for an 18 year old engine. Main thing is to stick with 5W-30 viscosity, be it GF5 or GF6-A, since GF6-A is backwards compatible with GF5 anyway.
Also, you are confusing things, the main drivers for development of thin viscosity GF6 grades were newer Turbocharged, downsized, Direct Injection engines. More importantly it also addressed oil dilution problems as well in certain downsized TGDI engines like 1.5 Turbo L15B7 in older Civics which prompted people to go for after market oil catch-cans and what not. Since GF6 version of 0W-20, that problem has also been largely addressed.
R18 is neither Turbo nor GDI.
Benefits that you get by putting 0W-20 in these newer TGDI engines do not "automatically" translate to an 18 year old engine just because you poured latest thinnest oil in it too.
You are basically wasting money on anything above GF5 5W-30 for an R18. Since GF5 is now obsolete, the natural transition is to GF6-A 5W-30.