First of all, again, thanks for contributing to Parf Edhellen and also thanks for all the well-formatted entries. (A minor technical detail, the Group should be “Neologisms”, not “Eldamo — fan inventions”, since your submissions do not appear on Eldamo).
Regarding the development of this word, I don’t think that ei > ai would apply here, since it only happens in final syllables. Also, I’d advise that you change the original form form miliktā- to milikta-: there are two very similar suffixes: -tā/-yā causatives (~ “make X”, e. g. tultā- “make come, cause to come → send for”) and -ta/-ya formatives (~ “do X”, e. g. KAY → caita- “to lie [down]” with no significant change in meaning). Here I believe you want a formative.