One of the Wikipedia phonetics pages that I find troublesome is the one intended to give guidance on how English is/should be transcribed phonemically in WP articles. It is called Help:IPA for English. The problem with it lies, I believe, in the fact that it tries to be all things to all people. In order to be able to represent all accents of English using a single set of quasi-phonemic symbols, it has opted for a set of diaphonemic symbols that allow for different interpretations according to which accent is being transcribed. I won’t go into all the difficulties that arise with this here, but at the bottom of the tables provided there is a section called “Reduced Vowels” which contains a box for two symbols for “vowels that are frequently dropped”. One is superscript schwa, which is used in several pronunciation dictionaries in cases like ‘bottle’: the transcription /bɒtəl/ can be pronounced with a schwa between /t/ and /l/, or with a syllabic /l/ immediately following the /t/. That seems OK. However, I have not until now been able to see the point of the superscript /i/, for which the WP article gives the example ‘nasturtium’. I have always been sure that this word would never have an /i/ in its pronunciation – to me that would sound like a caricature of a Victorian pedant. However, having made a note to that effect on the article’s Talk page, I have been put in my place by an editor who looked it up in OED and found that the pronunciation given there is /næˈstɜːʃ(ɪ)əm/. Oh dear.
This raises the question of whether we find optional /i/ or /ɪ/ in other English words. In the discussion on WP, I suggested that 'sentient' might be an example, as both CEPD and LPD list two-syllable and three-syllable pronunciations, but if the /i/ is elided, the preceding consonant becomes /ʃ/ or /tʃ/, so the two pronunciations don’t differ solely in the presence or absence of the vowel. The only other possibility I could come up with was the increasingly common (it seems to me) pronunciation of 'create', 'creating' as /kreɪt/, /kreɪtɪŋ/: this word could be transcribed with a superscript /i/ after /kr/. However, as far as I know, this pronunciation has not been noted in published work, so to use it here would presumably count as Original Research, which is not allowed in Wikipedia material.