If I understand the OP correctly, he/she is proposing an 18-cylinder, twin-row radial engine similar to the R-2180 Twin Hornet engine tested by Pratt & Whitney in 1930?
A twin-row based on Hornet cylinders is the logical, low-risk way to increase horsepower.
Twin Hornet was a twinned Hornet just in name. 14 cylinder engine R-2180 vs. 9 cylinder R-1690.
Plus the neglected thing that Twin Hornet never worked. Unlike the post war 'half R-4360' that also got the R-2180 name, alas it got no costumers
Trying to double output again by bolting together 4 rows was a complex procedure only perfected after WW2. Eventually Wright Turbo-Compound engines provided superlative fuel efficiency for (Cold War) RCAF Argus maritime patrol airplanes, but those corn-cob engines proved such maintenance-hits that they were
unpopular with civilian airlines.
Wright turbo-compound was not the 'corn cob', it used the 18 cyl R-3350 engine as basis. The 'corn cob, Pratt & Whitney R-4360 was a new engine, not rows of existing engines bolted together.
Sure, but AFAIK before the D-series showed up they had fixed the engine, the buffs you mention increased power and reliability, but it was unnecessary to make the Fw190 workable.
https://translate.google.com/translate?sl=auto&tl=en&js=y&prev=_t&hl=en&ie=UTF-8&u=https://de.wikipedia.org/wiki/Focke-Wulf_Fw_190#Fw_190_A-2&edit-text=&act=url
The Fw 190A-2 and A-3 shared the same installaton, for a different engine - 801C vs. 801D. The 801D when introduced with Fw 190A-3 was not reliable enough to meet the prescribed 1.42 ata and 2700 rpm, so these parameters were restricted until the relaibility was fixed by implementing the listed changes to the engine. Restriction was in force from March 1942 to October 1942 (when the listed chages are made). If the engine was operated above the restricted parameters, the engine will overheat.
Hopefuly your German is up to the speed: table