Thank you for your reply, @Andrew! Although I get your point, to me, this does not sound very consistent, either.
First, I have about 200 snippets with keywords that go back almost 15 years now. Back then, I followed a recommendation by TextExpander to use double characters at the start. In Alfreds Tips For Better Snippet Expansion, the same recommendation is included: "Use double characters (e.g. ttime)". All my keywords follow this rule and in my first example, the problem results just from the keywords "Oor" and "ssy".
Second, when one uses password-like keywords as you suggest, the mid-string-option seems obsolete at all, as there are very few cases in which non alphanumeric combinations occur in the middle of a word. So to me it seems like the middle-string-option only makes sense for keywords like in your example "ana".
Third, I am not sure what the use case for sequential snippets might be. Perhaps for writing code? For natural languages other than English the case I described is problematic: often, words consist of parts that can be 'snippetized' but often do require extra letters between them. Sequential snippets without mid-string expansion do not appear to be designed for natural language text production.
Having a "snippet key" like "§" in your case sounds like a very good idea to me. For me though, after getting used to lots of keywords over the years, it is not really an attractive option.
Could an extra option "allow sequential snippets" be a solution for both scenarios?