There are a number of things that are acceptable structure in a Toolbox file that need to be adjusted for FLEx. The sections here will address these.
Description of some structure differences between Toolbox SFM and FLEx
This applies for any reference field in FLEx (\cf, \sy, \an, \va, \mn, \re, \rn, etc.)
You can use the script SplitRefs.pl to divide fields.
Instructions for validating/fixing homograph numbers
Comments on validating sense numbers
You can check cross references using the script check_cf_special.pl
This script reports references without targets.
It converts targetless ones to use a different marker (\sy_NF, \cf_NF, etc.).
(Some parts of this are good to do early in the process, but it's probably best to delay actually applying the script until late in the process, just before importing)
Determine the set of values used in \ps
See if there are some values that are not appropriate for importing into FLEx (and therefore need to be "normalized").
Download and then edit FixPOS-NNN.pl so it can normalize the SFM file as decided.
Do all of this step, but if there are subentries of senses, delay applying the script. It's better to apply this after promoting subentries, just before importing. This will be noted in the instructions for handling subentries of senses.
Are subentries embedded or extracted?
Are there suitable references in both directions (\se in parent entry, \mn in daughter entry)
Are there any fields in an embedded subentry that FLEx doesn't expect?
Are there any subentries of senses? If so, follow the procedures in 6. Detour: Subentries of Senses