From the Wiki:
":*10%: '''Land unit''' in a region with an unbesieged town,
:*20%: '''Land unit''' in a region with an unbesieged city.
:**Minimum city level required is set in each game's City.str structure file by the parameter ''RplMinLevel'':
:*** AACW = 2
:*30%: '''Land unit''' in a region with an unbesieged Depot"
from the Dbase folder for structures changelog:
"changed to match AACW values"
This indicates to me that the City RplMinLvl is 2 (as in AACW), which is indeed the case. Villages are listed with the value of 1. So do other structures not mentioned that have a value of 1 also count as a Town/Village(T/V) for replacement? Apparently not, as Depots are listed with a value of 1, but are clearly described as giving a higher value of replacement than Cities or T/V. Also, a Stockade has a value of 2 (like a City), while the larger Fort and Redoubt both have a value of 1 (like a T/V). Clearly, the value does not reflect an ability to affect replacement as those listed in the Wiki. Perhaps the two values just differentiate between a City and the smaller T/V. Or the Wiki entry may be misleading and I am just dead wrong.
Since harbor level is described specifically and City level is not, this would indicate to me that City level is not a factor.
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