CSV export character set handling nothing change from eguide 2.54 to 2.6.
So I have no more suggestion from before comment.
A2.
Excel export template makes very limited.
You need change template for up to limit value.
For example eguide_reception.html change:
@@ -96,9 +96,9 @@
</form>
<p align='right'>
[
<a href="receipt.php?op=csv&eid=<{$eid}><{if $exid}>&sub=<{$exid}><{/if}>"><{$smarty.const._MD_CSV_OUT}></a>
- | <a href="export.php?eid=<{$eid}><{if $exid}>&sub=<{$exid}><{/if}>"><{$smarty.const._MD_EXPORT_OUT}></a>
+ | <a href="export.php?eid=<{$eid}><{if $exid}>&sub=<{$exid}><{/if}>&line=200"><{$smarty.const._MD_EXPORT_OUT}></a>
| <a href="sendinfo.php?eid=<{$eid}><{if $exid}>&sub=<{$exid}><{/if}>"><{$smarty.const._MD_INFO_MAIL}></a>
]
<a href="receipt.php?op=print&eid=<{$eid}><{if $exid}>&sub=<{$exid}><{/if}>"><img src="images/printer.png" alt="<{$smarty.const._PRINT}>" border="0" /></a>
</p>