Syllables are inherent to the spoken language and a native of that language will take a certain grouping of letters and turn it into a set of syllables according to that language’s rules.
In German, hyphenation generally follows syllables boundaries. About a decade ago, an article in a newspaper talked about the Chinese city of Shenyang but hyphenated it Sheny-ang. From a German point of view that could have been an acceptable syllable grouping if y is considered a vowel as ya (or ia) is not an acceptable diphthong, but Shen-yang (y as a half-vowel) would also have worked. For Chinese, only Shen-yang is possible because of the very restricted set of syllables. In Japanese, Shen-yan(g) or She-nyan(g) (strictly speaking, Japanese doesn’t have an ng sound unless k or g follow) would be possible with a y in the spelling; She-ni-an(g) or Shen-i-an(g) would strictly require an i in there.
As you maybe see, what will be seen depends on the language, and only what is possible will be produced. Another example is Japanese again, which only has open syllables or those ending in n. So when a Japanese tries to pronounce startling, that tends to end up somewhere near sutartolingu, a five-syllable (seven-mora) word. Thus, a speaker of your conlang will not even consider ep-se a possibility but will default to e-pse, if that is all the language does.
For the record, some languages with loose syllable rules still tend to end up with ambiguity. For example, the Finnish place Yli-Ii will have to have a hyphen to signify the short-long sequence. The German word Bakterien has an unusual syllable boundary between i and e (Bak-te-ri-en) while ie usually just signifies a long /i/ sound. Those things will need to be learnt at school, there is no way to predict.