do people actually say caerdydd with the emphasis on the first syllable. like i'd say it caer-dŷdd (well more like cyr-dŷdd tbh) and i've seen it written as caer-dydd in older texts. is this one of the words where emphasis isn't on the penultimate syllable, but it's still written in a way that makes it seem like the emphasis should be (you know like when people write penblwydd even though the emphasis is on the final syllable so the correct spelling is pen-blwydd. and mwynhau seems to always be pronounced mwynháu in my experience).
screenshot [kimkat.org](http://www.kimkat.org/amryw/1_gwenhwyseg/geiriadur-gwenhwyseg-saesneg_A_0231e.htm)