Sadira I find her to be overall a tough matchup because of a lack of proper anti airs with Mira. The way I try to play the matchup is keeping my distance from the beginning, and using Heavy bats to lock her down before going in, and then try and capitalize on all opportunities to keep her locked down. If she gets away or get her offense started, best to mist away as soon as you get a chance to do so safely (best bet would be to wait for the timing in which we is on the way down from her jump arc, already on top of you, and then mist up/forward or back/forward and air dash away, to try and return to neutral). This approach is kinda heavy on the blood damage, so try and snipe some of her jumps with a Medium embrace here and there as a good bet to recover some silver life and lock her down. For a Meaty, use s.MP for the best hurt box to stuff her shadow options on wake up (except for the wall bounce getaway, which had full inv).
Against riptor I haven’t encountered many issues, I don’t find the MU hard, but then again I haven’t played many. I’d use C.HP and M embrace to try and fight her off if she jumps too much, and make good use of light bats and s.MP for grounded footsies.
Cinder seems kinda troublesome if you let him go wild or give him too much space. Try to be on him at all times, put some jabs in between consecutive trailblazers and bait the DPs, punish them as late as possible with s.LK > trephine to spot if the Pilar is coming or not, and for a punish that works both against regular DP and fired up DP so you won’t risk going for the wrong punish.
Rash… Basically same strategy as above, but this time he only has a shadow reversal, so it’s even easier to bait and punish. I do have some issues dealing with wrecking ball because of Mira’s not so great anti air options, but a good way to avoid it is to just space it so you can dash under is it’s too high, or simply try not to be at that distance where he can do it low to the ground and hit you late, because then you’ll have to suck it up and block, because you won’t get a c.HP in there before he follows up with a jumping normal.
As for setups, check some of the videos compiled on the 1st post of the Mira tech thread by @R1stormrider. I personally either go for damage ender if I play the combo game and get a lockout or counter breaker for heavy damage, or I’ll go for the wall splat ender if I’m near the corner and need the life gain with shadow embrace follow up.
Other scenarios where I want a short combo into setup I’ll go for the juggle ender 90% of the time. Follow up with sweep for hard knockdown into Meaty crossup j.HK or air dash back into a front J.HK for a fake crossup. Or follow up with s.LK into heavy reaping for the recap, to catch them trying to break the sweep. Near the corner, I’ll go for wall splat for the setup (follow up with grab or sweep or counter breaker) while maintaining corner positioning.
Embrace ender… I don’t really ever use it, honestly, except to end an in-between rounds combo, for the life gain after the kill.