The creating scroll text says:
The creator must have prepared the spell to be scribed (or must know
the spell, in the case of a sorcerer or bard)
All others types of magic objects, except rings, share the same requirement. Also, there is the following text in the same page, concerning magic item construction requeriments:
A spell prerequisite may be provided by a character who has prepared
the spell (or who knows the spell, in the case of a sorcerer or bard),
or through the use of a spell completion or spell trigger magic item
or a spell-like ability that produces the desired spell effect. For
each day that passes in the creation process, the creator must expend
one spell completion item or one charge from a spell trigger item if
either of those objects is used to supply a prerequisite.
Both Wild arcana and Inspired Spell let you cast any spell in you class spell list even if you do not have it prepared or (if you are a spontaneous spell caster) know it. They do not grant knowledge of the spell or allow you to prepare it, they just allow you to cast the spell as if you had.
Most specific item creation rules (except rings) require the creator to specifically to have prepared/know the spell, as opposed to just being able to cast it. These rules do not concern with the source of the spells required to actually craft the item, only with the spells that the creator has prepared/known.
Also,the general rules of magic item creation says that the item spells requirements must be satisfied by a character that have prepared/know that spell(or have access to it from an item/sp ability). But those mythic abilities are not spell-like abilities, nor spell completion or spell trigger magic item, and they do not allow a caster to have prepared/know spells she does normally not have (just to cast any spell as if she had).
In conclusion, neither Wild arcana nor Inspired Spell those abilities automatically allow you to create magical items you would not otherwise be qualified to create. Also, note that while potions, spell-trigger, or spell-completion magic items cannot be created without meeting its prerequisites, the rest of items, like magic weapons, can. The creator just get a + 5 to DC of crafting the item each requirement not meet.
Of course, Magic Item creation rules were written way before Mythic adventures rules, so it is more than possible that what you propose is not covered by the rules just because there is not (and probably will never exist) an official revision of the old rules taking into account the new material. But that falls into DM decision territory.