I have done similar to create a “VWLR ex-US” (something I cannot buy from Vanguard). The percentages match current weightings and OCF comes to 0.13%, compared to VWRL’s 0.22%. I do not intend to make adjustments if the weighing of a componemt, say Japan, in VWRL changes by small amount, I will review in a year.
To permit users to more closely replicate the operation of an ETF there would need to be an option to “purchase/sell proportionally by shares”. ie to increase/decrease the number of shares owned in each slice of fhe pie by the same percentage.