

That’s a great summary. It covers practically all sources of inconsistency (sound changes, internal variation, etymological and fake etymological pressures, cosmetic-O).
Additionally there’s a small less-known rule that content words typically have 3+ letters, so sometimes you see “spurious” letters being added in. The link exemplifies it with ebb, add, egg, inn, bee, awe, buy, owe.
The link doesn’t load for me, it shows an error page. Thankfully the archive has the text in question.
Interesting run-down of the history of the expansion of the language. I must admit that I know practically nothing about Africa’s linguistic landscape (specially not for modern languages!), so for me it was highly informative.
This reminds me Nahuatl and Tupi in the Americas - due to colonisation they also expanded a bit, over other local languages. But unlike Swahili their expansion was short-lived (eventually the Iberian crowns enforced Spanish and Portuguese).
I also recommend people who are interested in the language to give the Swahili grammar Wikipedia page a check, IMO it’s fascinating.