Bel would enter Sage Mode as the birds perched on him flooded his body with Natural Energy, before beginning to gather more for him. His eyes would be surrounded by a blue highlight and the pupils of his eyes would change but that would be the only notable difference. Since his eyes were hidden by his blonde bangs it seems that it would not be noticed that he had entered Sage Mode at all, since the woman was not a Sage herself, being a Rinnegan user and all.
Presumably, since the wood clone dispersed upon summoning the Edo zombie, it must have contained only the minimum 20% of Machina’s chakra, leaving her with 80%. The chakra-cap that comes into effect while a zombie is in play would affect all versions of the woman though. Upon splitting further each copy of her would be down to 40% of her total chakra and since the Fission made it so she could only hold half as much chakra as normal. The 20% cap applied to that smaller pool size would likely make it so the 40% of her normal chakra pool was now effectively her max, she would not be able to have much more chakra then that. Of course with less than half of her chakra remaining she would begin to feel the effects of expending so much energy, starting to become tired, which would quickly lead to slower responses or irrational ones, all things which could lead to one’s death at a moment’s notice.
As her Edo zombie began to absorb the barrier it would crack around where he was siphoning it into himself, breaking off entirely before becoming absorbed. This piece of the barrier would be absorbed, yes, but it would leave a hole large enough that Tsuyo could no longer reach it with his Fūjutsu Kyūin. Since that jutsu cannot be used while moving he would have to float forward into another part of the barrier and begin to absorb it again. If course if he moved the chakra stored in the scroll would restore the part of the barrier he had just absorbed, making his efforts to absorb it entirely futile. Having holes in a barrier does destabilize it, yes, but the hole the Preta Path would make is relatively small on a barrier so large and since it would repair itself it should not be able to be made large enough to interfere with the barriers’ function.
Following this Bel would make a nearly instant series of three kata as Machina separated herself with the Fission Technique and used Senpō: Shōton: Suishō Meikyū no Jutsu. Crystal walls and flooring would instantaneously form around both of the copies of Machina. Since the two of them were ten feet apart from one another (never stated how far the copy was from you, as Fission Jutsu causes the clone to be ejected from your own body) the walls that seemed to spawn from thin air would separate them in an attempt to keep them from rejoining. Crystal flooring would form from the sand several feet under them as well as the air above, so if they attempted to go downward or upward they would be thwarted as well. The crystal floor under one of them would rise up, attempting to separate the two even further. The end result of this jutsu was a massive, completely walled in, crystal maze that was shaped like a massive cut emerald. It was quite impressive being several stories tall and relatively the same size as the canon variant was when used by Guren. The reflective, chakra filled surfaces would confound the Sharingan or Rinnegan eyes the woman possessed and the walls, floors and every other part of the maze was at the minimum three feet thick, all the way up to the outer walls of the maze which were fifteen feet thick. The normal form of this technique is already resistant to all but the strongest attacks, so of course the Senjutsu version would have an even higher amount of durability, among some other new tricks. The maze itself is of course a trick, there was no path that lead out of it, and no path that would lead the two women back to each other. It was merely laid out this way to make them waste their time and energy.
One fun new addition that would likely be noticed immediately is the fact that, much like Doton Kekkai: Dorō Dōmu, Machina would find her chakra being drained for as long as she was contained within the crystal structure. Since there were two of her, the crystal would drain her of chakra at double speed, since it had two sources to tap into.
Bel had to ascend further into the air to avoid being sealed within the maze himself and after completing the three kata for the crystal labyrinth he would make one more kata and generate a flat floating crystal mirror that would be faced toward Machina’s Edo Tensei zombie, between it and Belphegor.