Eric would continue to attempt to shadow sew his opponent until he could no longer. It would be very likely that he would also succeed in very seriously injuring her if not outright killing her as a result of the shadow spikes completely impaling her at almost every angle reasonably possible, using the shadows on her body as the point of origin for the shadows. He would then proceed to try to escape the earthen dome by burrowing underneath it, using the space that was allotted by the ground range of Masane's seal.That is the short and dirty of it. The longer, necessary bit, is as such:
Eric specifically targeted Masane the moment she would become tangible again. His actions were tailored to the original post of Masane attempting to summon her sphinx. As a result, Masane's shadow would not have been cursed, at the earliest, until she began performing the handseals for the summoning technique, and at the latest, the instant she went to the last step of actually using the jutsu. This is where the scenarios branch, so let the first instance be A and the second instance be B. Taking her re-post exactly as it is written without filling in any logic details can be considered instance C.
A) Near the beginning of her summoning effort, Masane realizes that she has been shadow cursed (as can be read in her repost, as she did not react until her shadow was cursed) and decides to activate Kamui in order to teleport herself to the presumed safety of her pocket dimension. The handsign required for shadow sewing would have already been made by this point, so no additional time would be required to execute that technique immediately after the cursing.
It is stated in my post that all of this would be done by the time Masane finished her summoning technique. She does not take very long to do this action, I doubt any would argue otherwise. Now, her Kamui, senjutsu-enhanced or not, would take time to complete, and even then, she is teleported with her shadow in-tact; as a result, turning intangible would have done her absolutely no favors, and even in her current course of action, there would be just enough time for the spikes to do some harm before she fully escaped, considering that it takes more time for the user to warp themselves than other objects. The only thing going to her pocket dimension would do would be to render Eric temporarily unable to to take advantage of her cursed shadow until she re-opened the Kamui portal.
B) This scenario is very similar to the above, but her own shadow would not be cursed until she prepares to at last summon her sphinx. Now, considering the timing of this, she would have likely had to first stop her summoning technique (having already done most of the handsigns and thus molded her chakra for this summoning) and then activate her Kamui. This would add a very small amount of time to the evasion, but it would be a time she could not afford considering the rapid execution of the techniques. Without a doubt in this scenario, she would be dead, and her Kamui attempt would outright fail.
C) Taking her repost for exactly as it is stated, she would only act once her shadow was cursed. Considering the execution of the shadow sewing immediately afterwards, she would then not be able to Kamui in time to save herself from being sown from the inside-out, especially if she had already performed the set of handsigns for the summoning technique:
She would again weave the seals and summon the beast Berial.
No matter the scenario, Masane cannot get off scotch-free, and more likely than not, would likely be killed at this juncture. Severe injury is quite likely as well, but to escape without any damage, I feel, is outright god-mode.
Now, for the remainder of my post:
Regardless of the success of his attack, Eric needed to escape this accursed barrier of hers. He needed to be ready to strike at Masane at any moment, but at the same time, if she decided to wait him out in her pocket dimension, he would be in serious trouble. As a result, he needed to break this accursed fuinjutsu that she had on the floor.
It absorbed chakra, but as his shadow sensory's "darkness" (it being hindered in areas where chakra absorption is active) could tell him, there was a small area on the floor where he could operate without having his chakra sapped judiciously. Moving himself to this small section, the Nara once again activated his tail beast cloak, Version 2, though this time, he would be taking advantage of the increased strength. Since the senjutsu-enhanced dome was stated only to be the walls and the ceiling, then it can be presumed that the ground was not also transformed in this manner.
Though it was a risk, Eric needed to get out of the situation that he was on. Using his increased strength and the chakra arms, he would attempt to burrow into the ground and out. Considering that the seal spread from her location near one of the walls of the earthen barrier outwards along the ground about 45 meters, then that meant that his safe area would likely be on the exact opposite end of the dome area.
As a result, his aim would be to pop up on the other side of the earthen dome, just on the other side and prepare running forward on all fours in an attempt to leave the space-time barrier restriction area.
Of course, if Masane decided to return at any point during this, Eric would at once stop and use shadow sewing to try to do her and potentially her sphinx in (since it's shadow would have been cursed as well, since its shadow emerged from the shadow of Masane). Again, most of this second part would only be very important if Masane was not killed in the earlier attack. Best to cover my bases rather than just assume that the auto-hit attempt would go in my favor.